A country called Berland consists of n cities, numbered with integer numbers from 1 to n. Some of them are connected by bidirectional roads. Each road has some length. There is a path from each city to any other one by these roads. According to some Super Duper Documents, Berland is protected by the Super Duper Missiles. The exact position of the Super Duper Secret Missile Silos is kept secret but Bob managed to get hold of the information. That information says that all silos are located exactly at a distance l from the capital. The capital is located in the city with number s.

The documents give the formal definition: the Super Duper Secret Missile Silo is located at some place (which is either city or a point on a road) if and only if the shortest distance from this place to the capital along the roads of the country equals exactly l.

Bob wants to know how many missile silos are located in Berland to sell the information then to enemy spies. Help Bob.

Input

The first line contains three integers n, m and s (2 ≤ n ≤ 105, <image>, 1 ≤ s ≤ n) — the number of cities, the number of roads in the country and the number of the capital, correspondingly. Capital is the city no. s. 

Then m lines contain the descriptions of roads. Each of them is described by three integers vi, ui, wi (1 ≤ vi, ui ≤ n, vi ≠ ui, 1 ≤ wi ≤ 1000), where vi, ui are numbers of the cities connected by this road and wi is its length. The last input line contains integer l (0 ≤ l ≤ 109) — the distance from the capital to the missile silos. It is guaranteed that: 

  * between any two cities no more than one road exists; 
  * each road connects two different cities; 
  * from each city there is at least one way to any other city by the roads. 

Output

Print the single number — the number of Super Duper Secret Missile Silos that are located in Berland.

Examples

Input

4 6 1
1 2 1
1 3 3
2 3 1
2 4 1
3 4 1
1 4 2
2


Output

3


Input

5 6 3
3 1 1
3 2 1
3 4 1
3 5 1
1 2 6
4 5 8
4


Output

3

Note

In the first sample the silos are located in cities 3 and 4 and on road (1, 3) at a distance 2 from city 1 (correspondingly, at a distance 1 from city 3).

In the second sample one missile silo is located right in the middle of the road (1, 2). Two more silos are on the road (4, 5) at a distance 3 from city 4 in the direction to city 5 and at a distance 3 from city 5 to city 4.
import static java.lang.Math.*;
import java.util.*;
import java.io.*;


public class D {

    class Pair implements Comparable<Pair> {
        int idV, d;
        public Pair(int idV, int d) {
            this.idV = idV; this.d = d;
        }
        public int compareTo(Pair other) {
            if (d==-1) return 1;
            if (other.d==-1) return -1;
            return d-other.d;
        }
    }
    
    
    int[] dijkstra(LinkedList<Pair>[] adjacencyList, int start) {
        
        int n = adjacencyList.length;       
        int[] dist = new int[n];
        Arrays.fill(dist,-1);
        dist[start] = 0;
        PriorityQueue<Pair> q = new PriorityQueue<Pair>();
        q.add(new Pair(start, 0));
        
        while (!q.isEmpty()) {
            Pair curr = q.poll();
            if (dist[curr.idV]!=curr.d) continue;
            int currIdV = curr.idV;
            for (Pair neighbor: adjacencyList[currIdV]) {
                int x = dist[currIdV] + neighbor.d;
                if (dist[neighbor.idV]==-1 || x<dist[neighbor.idV]) {
                    q.offer(new Pair(neighbor.idV,x));
                    dist[neighbor.idV] = x;
                }
            }
            
        }
        
        return dist;
    }
    
    public void solve() throws Exception {
        
        int n = nextInt(), m = nextInt(), s = nextInt();
        LinkedList<Pair>[] ll = new LinkedList[n];
        for (int i=0; i<n; ++i) ll[i] = new LinkedList<Pair>();
        for (int i=0; i<m; ++i) {
            int u = nextInt(), v = nextInt(), w = nextInt();
            ll[u-1].addLast(new Pair(v-1,w));
            ll[v-1].addLast(new Pair(u-1,w));
        }
        
        int[] dist = dijkstra(ll, s-1);
//      debug(dist);
        
        int d = nextInt();
        int res = 0;
        for (int x: dist) if (x==d) res++;
        
        HashSet<Long> mid = new HashSet<Long>();
        
        for (int i=0; i<n; ++i) {
            for (Pair p: ll[i]) {
                if (dist[i]<d && dist[i]+p.d>d && dist[p.idV]+p.d-(d-dist[i])>=d) {
                    int w = p.d;
                    int x = i<p.idV ? d-dist[i] : w-(d-dist[i]);
                    if (!mid.contains(minL(i,p.idV)*1000000000000L + maxL(i,p.idV)*1000000 + x)) {
                        res++;
                        mid.add(minL(i,p.idV)*1000000000000L + maxL(i,p.idV)*1000000 + x);
                    }
                }
            }
        }
            
        
        println(res);
        
    }

    

    ////////////////////////////////////////////////////////////////////////////
    
    boolean showDebug = true;
    static boolean useFiles = false;
    static String inFile = "input.txt";
    static String outFile = "output.txt";

    double EPS = 1e-7;
    int INF = Integer.MAX_VALUE;
    long INFL = Long.MAX_VALUE;
    double INFD = Double.MAX_VALUE;

    
    int absPos(int num) {
        return num<0 ? 0:num;
    }
    long absPos(long num) {
        return num<0 ? 0:num;
    }
    double absPos(double num) {
        return num<0 ? 0:num;
    }
    
    int min(int... nums) {
        int r = Integer.MAX_VALUE;
        for (int i: nums)
            if (i<r) r=i;
        return r;
    }
    int max(int... nums) {
        int r = Integer.MIN_VALUE;
        for (int i: nums)
            if (i>r) r=i;
        return r;
    }
    long minL(long... nums) {
        long r = Long.MAX_VALUE;
        for (long i: nums)
            if (i<r) r=i;
        return r;
    }
    long maxL(long... nums) {
        long r = Long.MIN_VALUE;
        for (long i: nums)
            if (i>r) r=i;
        return r;
    }
    double minD(double... nums) {
        double r = Double.MAX_VALUE;
        for (double i: nums)
            if (i<r) r=i;
        return r;
    }
    double maxD(double... nums) {
        double r = Double.MIN_VALUE;
        for (double i: nums)
            if (i>r) r=i;
        return r;
    }
    
    long sumArr(int[] arr) {
        long res = 0;
        for (int i: arr)
            res+=i;
        return res;
    }
    long sumArr(long[] arr) {
        long res = 0;
        for (long i: arr)
            res+=i;
        return res;
    }
    double sumArr(double[] arr) {
        double res = 0;
        for (double i: arr)
            res+=i;
        return res;
    }

    long partsFitCnt(long partSize, long wholeSize) {
        return (partSize+wholeSize-1)/partSize;
    }

    boolean odd(long num) {
        return (num&1)==1;
    }
    
    boolean hasBit(int num, int pos) {
        return (num&(1<<pos))>0;
    }

    long binpow(long a, int n) {
        long r = 1;
        while (n>0) {
            if ((n&1)!=0) r*=a;
            a*=a;
            n>>=1;
        }
        return r;
    }

    boolean isLetter(char c) {
        return (c>='a' && c<='z') || (c>='A' && c<='Z');
    }
    boolean isLowercase(char c) {
        return (c>='a' && c<='z');
    }
    boolean isUppercase(char c) {
        return (c>='A' && c<='Z');
    }
    boolean isDigit(char c) {
        return (c>='0' && c<='9');
    }
    
    boolean charIn(String chars, String s) {
        if (s==null) return false;
        if (chars==null || chars.equals("")) return true;
        for (int i=0; i<s.length(); ++i)
            for (int j=0; j<chars.length(); ++j)
                if (chars.charAt(j)==s.charAt(i)) return true;
        return false;
    }
    
    String stringn(String s, int n) {
        if (n<1 || s==null) return "";
        StringBuilder sb = new StringBuilder(s.length()*n);
        for (int i=0; i<n; ++i) sb.append(s);
        return sb.toString();
    }
    String str(Object o) {
        if (o==null) return "";
        return o.toString();
    }


    long timer = System.currentTimeMillis();
    void startTimer() {
        timer = System.currentTimeMillis();
    }
    void stopTimer() {
        System.err.println("time: "+(System.currentTimeMillis()-timer)/1000.0);
    }


    static class InputReader {
        private byte[] buf;
        private int bufPos = 0, bufLim = -1;
        private InputStream stream;
        public InputReader(InputStream stream, int size) {
            buf = new byte[size];
            this.stream = stream;
        }
        private void fillBuf() throws IOException {
            bufLim = stream.read(buf);
            bufPos = 0;
        }
        char read() throws IOException {
            if (bufPos>=bufLim) fillBuf(); 
            return (char)buf[bufPos++];
        }
        boolean hasInput() throws IOException {
            if (bufPos>=bufLim) fillBuf();
            return bufPos<bufLim;
        }
    }
    
    static InputReader inputReader;
    static BufferedWriter outputWriter;

    char nextChar() throws IOException {
        return inputReader.read();
    }
    char nextNonWhitespaceChar() throws IOException {
        char c = inputReader.read();
        while (c<=' ') c=inputReader.read();
        return c;
    }
    String nextWord() throws IOException {
        StringBuilder sb = new StringBuilder();
        char c = inputReader.read();
        while (c<=' ') c=inputReader.read();
        while (c>' ') {
            sb.append(c);
            c = inputReader.read();
        }
        return new String(sb);
    }
    String nextLine() throws IOException {
        StringBuilder sb = new StringBuilder();
        char c = inputReader.read();
        while (c<=' ') c=inputReader.read();
        while (c!='\n' && c!='\r') {
            sb.append(c);
            c = inputReader.read();
        }
        return new String(sb);
    }
    int nextInt() throws IOException {
        int r = 0;
        char c = nextNonWhitespaceChar();
        boolean neg = false;
        if (c=='-') neg=true;
        else r=c-48;
        c = nextChar();
        while (c>='0' && c<='9') {
            r*=10;
            r+=c-48;
            c=nextChar();
        }
        return neg ? -r:r;
    }
    long nextLong() throws IOException {
        long r = 0;
        char c = nextNonWhitespaceChar();
        boolean neg = false;
        if (c=='-') neg=true;
        else r = c-48;
        c = nextChar();
        while (c>='0' && c<='9') {
            r*=10L;
            r+=c-48L;
            c=nextChar();
        }
        return neg ? -r:r;
    }
    double nextDouble() throws NumberFormatException, IOException {
        return Double.parseDouble(nextWord());
    }
    int[] nextArr(int size) throws NumberFormatException, IOException {
        int[] arr = new int[size];
        for (int i=0; i<size; ++i)
            arr[i] = nextInt();
        return arr;
    }
    long[] nextArrL(int size) throws NumberFormatException, IOException {
        long[] arr = new long[size];
        for (int i=0; i<size; ++i)
            arr[i] = nextLong();
        return arr;
    }
    double[] nextArrD(int size) throws NumberFormatException, IOException {
        double[] arr = new double[size];
        for (int i=0; i<size; ++i)
            arr[i] = nextDouble();
        return arr;
    }
    String[] nextArrS(int size) throws NumberFormatException, IOException {
        String[] arr = new String[size];
        for (int i=0; i<size; ++i)
            arr[i] = nextWord();
        return arr;
    }
    char[] nextArrCh(int size) throws IOException {
        char[] arr = new char[size];
        for (int i=0; i<size; ++i)
            arr[i] = nextNonWhitespaceChar();
        return arr;
    }
    char[][] nextArrCh(int rows, int columns) throws IOException {
        char[][] arr = new char[rows][columns];
        for (int i=0; i<rows; ++i)
            for (int j=0; j<columns; ++j)
                arr[i][j] = nextNonWhitespaceChar();
        return arr;
    }
    char[][] nextArrChBorders(int rows, int columns, char border) throws IOException {
        char[][] arr = new char[rows+2][columns+2];
        for (int i=1; i<=rows; ++i)
            for (int j=1; j<=columns; ++j)
                arr[i][j] = nextNonWhitespaceChar();
        for (int i=0; i<columns+2; ++i) {
            arr[0][i] = border;
            arr[rows+1][i] = border;
        }
        for (int i=0; i<rows+2; ++i) {
            arr[i][0] = border;
            arr[i][columns+1] = border;
        }
        return arr;
    }

    void printf(String format, Object... args) throws IOException {
        outputWriter.write(String.format(format, args));
    }
    void print(Object o) throws IOException {
        outputWriter.write(o.toString());
    }
    void println(Object o) throws IOException {
        outputWriter.write(o.toString());
        outputWriter.newLine();
    }
    void print(Object... o) throws IOException {
        for (int i=0; i<o.length; ++i) {
            if (i!=0) outputWriter.write(' ');
            outputWriter.write(o[i].toString());
        }
    }
    void println(Object... o) throws IOException {
        print(o);
        outputWriter.newLine();
    }
    void printn(Object o, int n) throws IOException {
        String s = o.toString();
        for (int i=0; i<n; ++i) {
            outputWriter.write(s);
            if (i!=n-1) outputWriter.write(' ');
        }
    }
    void printnln(Object o, int n) throws IOException {
        printn(o, n);
        outputWriter.newLine();
    }
    void printArr(int[] arr) throws IOException {
        for (int i=0; i<arr.length; ++i) {
            if (i!=0) outputWriter.write(' ');
            outputWriter.write(Integer.toString(arr[i]));
        }
    }
    void printArr(long[] arr) throws IOException {
        for (int i=0; i<arr.length; ++i) {
            if (i!=0) outputWriter.write(' ');
            outputWriter.write(Long.toString(arr[i]));
        }
    }
    void printArr(double[] arr) throws IOException {
        for (int i=0; i<arr.length; ++i) {
            if (i!=0) outputWriter.write(' ');
            outputWriter.write(Double.toString(arr[i]));
        }
    }
    void printArr(String[] arr) throws IOException {
        for (int i=0; i<arr.length; ++i) {
            if (i!=0) outputWriter.write(' ');
            outputWriter.write(arr[i]);
        }
    }
    void printArr(char[] arr) throws IOException {
        for (char c: arr) outputWriter.write(c);
    }
    void printlnArr(int[] arr) throws IOException {
        printArr(arr);
        outputWriter.newLine();
    }
    void printlnArr(long[] arr) throws IOException {
        printArr(arr);
        outputWriter.newLine();
    }
    void printlnArr(double[] arr) throws IOException {
        printArr(arr);
        outputWriter.newLine();
    }
    void printlnArr(String[] arr) throws IOException {
        printArr(arr);
        outputWriter.newLine();
    }
    void printlnArr(char[] arr) throws IOException {
        printArr(arr);
        outputWriter.newLine();
    }
    void halt(Object... o) throws IOException {
        if (o.length!=0) println(o);
        outputWriter.flush(); outputWriter.close();
        System.exit(0);
    }
    
    void debug(Object... o) {
        if (showDebug) System.err.println(Arrays.deepToString(o));
    }


    public static void main(String[] args) throws Exception {
        Locale.setDefault(Locale.US);
        if (!useFiles) {
            inputReader = new InputReader(System.in, 1<<16);
            outputWriter = new BufferedWriter(new OutputStreamWriter(System.out), 1<<16);
        } else {
            inputReader = new InputReader(new FileInputStream(new File(inFile)), 1<<16);
            outputWriter = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(new File(outFile))), 1<<16);
        }
        new D().solve();
        outputWriter.flush(); outputWriter.close();
    }
}
