There is an infinite sequence consisting of all positive integers in the increasing order: p = {1, 2, 3, ...}. We performed n swap operations with this sequence. A swap(a, b) is an operation of swapping the elements of the sequence on positions a and b. Your task is to find the number of inversions in the resulting sequence, i.e. the number of such index pairs (i, j), that i < j and pi > pj.

Input

The first line contains a single integer n (1 ≤ n ≤ 105) — the number of swap operations applied to the sequence.

Each of the next n lines contains two integers ai and bi (1 ≤ ai, bi ≤ 109, ai ≠ bi) — the arguments of the swap operation.

Output

Print a single integer — the number of inversions in the resulting sequence.

Examples

Input

2
4 2
1 4


Output

4


Input

3
1 6
3 4
2 5


Output

15

Note

In the first sample the sequence is being modified as follows: <image>. It has 4 inversions formed by index pairs (1, 4), (2, 3), (2, 4) and (3, 4).
import java.io.*;
import java.util.*;
import java.math.*;

public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        OutputWriter out = new OutputWriter(outputStream);
        Task solver = new Task();
        solver.solve(1, in, out);
        out.close();
    }
}

class Task {
	
	public void solve(int testNumber, InputReader in, OutputWriter out) {
    	int n=in.readInt(), idx=1;
    	Map<Integer, Integer> map=new TreeMap<>(), ItoR=new TreeMap<>(), RtoI=new TreeMap<>();
    	Set<Integer> set=new TreeSet<>();
    	while (n-->0) {
    		int a=in.readInt(), b=in.readInt(), pa=map.containsKey(a)?map.get(a):a, pb=map.containsKey(b)?map.get(b):b;
    		map.put(a, pb);
    		map.put(b, pa);
    	}
    	set.addAll(map.keySet());
    	for (int i: map.keySet()) set.add(i-1);
    	for (int i: set) {
    		RtoI.put(i, idx);
    		ItoR.put(idx++, i);
    	}
    	int[] bit=new int[idx];
    	long ret=0;
    	idx=0;
    	for (int i: map.keySet()) {
    		if (!map.containsKey(i-1)) {
    			ret+=1L*(query(bit, bit.length-1)-query(bit, RtoI.get(i-1)))*(i-1-idx);
    			update(bit, RtoI.get(i-1), i-1-idx);
    		}
    		ret+=1L*(query(bit, bit.length-1)-query(bit, RtoI.get(map.get(i))));
    		update(bit, RtoI.get(map.get(i)), 1);
    		idx=i;
    		//out.printLine(i, map.get(i), ret);
    	}
    	out.printLine(ret);
    }
	
	void update(int[] bit, int pos, int val) {
		for (; pos<bit.length; pos+=pos&-pos) bit[pos]+=val;
	}
	
	int query(int[] bit, int pos) {
		int ret=0;
		for (; pos>0; pos-=pos&-pos) ret+=bit[pos];
		return ret;
	}
}

class InputReader {
    private boolean finished = false;

    private InputStream stream;
    private byte[] buf = new byte[1024];
    private int curChar;
    private int numChars;
    private SpaceCharFilter filter;

    public InputReader(InputStream stream) {
            this.stream = stream;
    }

    public int read() {
            if (numChars == -1)
                    throw new InputMismatchException();
            if (curChar >= numChars) {
                    curChar = 0;
                    try {
                            numChars = stream.read(buf);
                    } catch (IOException e) {
                            throw new InputMismatchException();
                    }
                    if (numChars <= 0)
                            return -1;
            }
            return buf[curChar++];
    }

    public int peek() {
            if (numChars == -1)
                    return -1;
            if (curChar >= numChars) {
                    curChar = 0;
                    try {
                            numChars = stream.read(buf);
                    } catch (IOException e) {
                            return -1;
                    }
                    if (numChars <= 0)
                            return -1;
            }
            return buf[curChar];
    }

    public int readInt() {
            int c = read();
            while (isSpaceChar(c))
                    c = read();
            int sgn = 1;
            if (c == '-') {
                    sgn = -1;
                    c = read();
            }
            int res = 0;
            do {
                    if (c < '0' || c > '9')
                            throw new InputMismatchException();
                    res *= 10;
                    res += c - '0';
                    c = read();
            } while (!isSpaceChar(c));
            return res * sgn;
    }

    public long readLong() {
            int c = read();
            while (isSpaceChar(c))
                    c = read();
            int sgn = 1;
            if (c == '-') {
                    sgn = -1;
                    c = read();
            }
            long res = 0;
            do {
                    if (c < '0' || c > '9')
                            throw new InputMismatchException();
                    res *= 10;
                    res += c - '0';
                    c = read();
            } while (!isSpaceChar(c));
            return res * sgn;
    }

    public String readString() {
            int c = read();
            while (isSpaceChar(c))
                    c = read();
            StringBuilder res = new StringBuilder();
            do {
                    if (Character.isValidCodePoint(c))
                            res.appendCodePoint(c);
                    c = read();
            } while (!isSpaceChar(c));
            return res.toString();
    }

    public boolean isSpaceChar(int c) {
            if (filter != null)
                    return filter.isSpaceChar(c);
            return isWhitespace(c);
    }

    public static boolean isWhitespace(int c) {
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
    }

    private String readLine0() {
            StringBuilder buf = new StringBuilder();
            int c = read();
            while (c != '\n' && c != -1) {
                    if (c != '\r')
                            buf.appendCodePoint(c);
                    c = read();
            }
            return buf.toString();
    }

    public String readLine() {
            String s = readLine0();
            while (s.trim().length() == 0)
                    s = readLine0();
            return s;
    }

    public String readLine(boolean ignoreEmptyLines) {
            if (ignoreEmptyLines)
                    return readLine();
            else
                    return readLine0();
    }

    public BigInteger readBigInteger() {
            try {
                    return new BigInteger(readString());
            } catch (NumberFormatException e) {
                    throw new InputMismatchException();
            }
    }

    public char readCharacter() {
            int c = read();
            while (isSpaceChar(c))
                    c = read();
            return (char) c;
    }

    public double readDouble() {
            int c = read();
            while (isSpaceChar(c))
                    c = read();
            int sgn = 1;
            if (c == '-') {
                    sgn = -1;
                    c = read();
            }
            double res = 0;
            while (!isSpaceChar(c) && c != '.') {
                    if (c == 'e' || c == 'E')
                            return res * Math.pow(10, readInt());
                    if (c < '0' || c > '9')
                            throw new InputMismatchException();
                    res *= 10;
                    res += c - '0';
                    c = read();
            }
            if (c == '.') {
                    c = read();
                    double m = 1;
                    while (!isSpaceChar(c)) {
                            if (c == 'e' || c == 'E')
                                    return res * Math.pow(10, readInt());
                            if (c < '0' || c > '9')
                                    throw new InputMismatchException();
                            m /= 10;
                            res += (c - '0') * m;
                            c = read();
                    }
            }
            return res * sgn;
    }

    public boolean isExhausted() {
            int value;
            while (isSpaceChar(value = peek()) && value != -1)
                    read();
            return value == -1;
    }

    public String next() {
            return readString();
    }

    public SpaceCharFilter getFilter() {
            return filter;
    }

    public void setFilter(SpaceCharFilter filter) {
            this.filter = filter;
    }

    public interface SpaceCharFilter {
            public boolean isSpaceChar(int ch);
    }
}

class OutputWriter {
    private final PrintWriter writer;

    public OutputWriter(OutputStream outputStream) {
            writer = new PrintWriter(new BufferedWriter(new OutputStreamWriter(outputStream)));
    }

    public OutputWriter(Writer writer) {
            this.writer = new PrintWriter(writer);
    }

    public void print(char[] array) {
            writer.print(array);
    }

    public void print(Object...objects) {
            for (int i = 0; i < objects.length; i++) {
                    if (i != 0)
                            writer.print(' ');
                    writer.print(objects[i]);
            }
    }

public void print(int[] array) {
    for (int i = 0; i < array.length; i++) {
        if (i != 0)
            writer.print(' ');
        writer.print(array[i]);
    }
}

public void print(long[] array) {
    for (int i = 0; i < array.length; i++) {
        if (i != 0)
            writer.print(' ');
        writer.print(array[i]);
    }
}

public void print(Collection<Integer> collection) {
            boolean first = true;
            for (int i: collection) {
                    if (first)
                            first = false;
                    else
                            writer.print(' ');
                    writer.print(i);
            }
    }

    public void printLine(int[] array) {
    print(array);
    writer.println();
}

public void printLine(long[] array) {
    print(array);
    writer.println();
}

public void printLine(Collection<Integer> collection) {
            print(collection);
            writer.println();
    }

    public void printLine() {
            writer.println();
    }

public void printLine(Object...objects) {
            print(objects);
            writer.println();
    }

    public void print(char i) {
            writer.print(i);
    }

    public void printLine(char i) {
            writer.println(i);
    }

    public void printLine(char[] array) {
            writer.println(array);
    }

    public void printFormat(String format, Object...objects) {
            writer.printf(format, objects);
    }

    public void close() {
            writer.close();
    }

    public void flush() {
            writer.flush();
    }

    public void print(long i) {
            writer.print(i);
    }

    public void printLine(long i) {
            writer.println(i);
    }

    public void print(int i) {
            writer.print(i);
    }

    public void printLine(int i) {
            writer.println(i);
    }
}
