You are given a string s=s_1s_2... s_n of length n, which only contains digits 1, 2, ..., 9.

A substring s[l ... r] of s is a string s_l s_{l + 1} s_{l + 2} … s_r. A substring s[l ... r] of s is called even if the number represented by it is even. 

Find the number of even substrings of s. Note, that even if some substrings are equal as strings, but have different l and r, they are counted as different substrings.

Input

The first line contains an integer n (1 ≤ n ≤ 65000) — the length of the string s.

The second line contains a string s of length n. The string s consists only of digits 1, 2, ..., 9.

Output

Print the number of even substrings of s.

Examples

Input


4
1234


Output


6

Input


4
2244


Output


10

Note

In the first example, the [l, r] pairs corresponding to even substrings are: 

  * s[1 ... 2]
  * s[2 ... 2]
  * s[1 ... 4]
  * s[2 ... 4]
  * s[3 ... 4]
  * s[4 ... 4] 



In the second example, all 10 substrings of s are even substrings. Note, that while substrings s[1 ... 1] and s[2 ... 2] both define the substring "2", they are still counted as different substrings.
import javax.print.DocFlavor;
import java.beans.IntrospectionException;
import java.io.*;
import java.lang.reflect.Array;
import java.math.BigInteger;
import java.util.*;
import java.lang.*;
import static java.lang.Math.*;
public class Main implements Runnable {

    public static void main(String[] args) {
        new Thread(null, new Main(), "Check2", 1 << 28).start();// to increse stack size in java
    }
    void init(ArrayList <pair2> adj[],int n){
        for(int i=0;i<=n;i++)adj[i]=new ArrayList<>();
    }
    static long mod = (long) (1e9 + 7);
    public void run() {
        InputReader in = new InputReader(System.in);
        PrintWriter w = new PrintWriter(System.out);
        int n = in.nextInt();
        char c[] = in.next().toCharArray();
        long ans = 0;
        for (int i=0;i<c.length;i++){
            if((c[i]-'0')%2==0)ans+=(i+1);
        }
        w.println(ans);

        w.close();
    }
    static class obj{
        long val;
            int lvl;
        obj(long val,int lvl){
            this.val = val;
            this.lvl = lvl;
        }
    }
    public static class lca {



        ArrayList <Integer> list[];
        int table[][];
        int lvl[];
        int bit;
        int n;
        public void dfs2(int i,int v[],int parent,int par[]){
            if(v[i]==1)return;

            v[i]=1;
            par[i]=parent;

            for(Integer ne:list[i])
            {
                dfs2(ne,v,i,par);
            }

        }


        public int log2(int n){
            return (int)(Math.ceil(Math.log10(n)/Math.log10(2)));
        }
        public lca(ArrayList <Integer> a[],int n)
        {
            list=a;
            bit=log2(n+1);
            lvl=new int[n+1];

            table=new int[n+1][bit+1];
            this.n=n;
        }

        public void build(int par[])
        {
            for(int i=1;i<=n;i++)table[i][0]=i;
            for(int i=1;i<=n;i++)table[i][1]=par[i];
            for(int i=2;i<=bit;i++){
                for(int j=1;j<=n;j++){
                    table[j][i]=table[table[j][i-1]][i-1];
                }
            }

            int v[]=new int[n+1];
            dfs(1,v,0);
        }
        public void dfs(int i,int v[],int level){
            if(v[i]==1)return;

            lvl[i]=level;
            v[i]=1;
            for(Integer ne:list[i]){

                dfs(ne,v,level+1);
            }

        }

        public int kthancestor(int node,int k){

            int ans=node;
            for(int j=0;j<=bit;j++){

                if((k&(1<<j))!=0&&j!=bit){
                    ans=table[ans][j+1];
                }

            }
            return ans;

        }
        public int LCA(int node1,int node2){

            if(lvl[node1]>lvl[node2]){
                node1=kthancestor(node1,lvl[node1]-lvl[node2]);
            }
            else if(lvl[node1]<lvl[node2]){
                node2=kthancestor(node2,lvl[node2]-lvl[node1]);
            }
            if(node1==node2){
                return node1;
            }

            for(int i=bit;i>=0;i--){

                if(table[node1][i]!=table[node2][i]){

                    node1=table[node1][i];
                    node2=table[node2][i];

                }

            }

            return table[node1][1];
        }

    }
    int step, size;
    int frq[], dp[];

    int rec(int pos) {

        if(pos < 0) return 0;
        if(dp[pos] != -1) return dp[pos];
        int res = rec(pos - 1);
        res = max(res, (pos * frq[pos] + rec(pos - step - 1)));
        dp[pos] = res;
        return dp[pos];
    }
    class pair2{
        int a;
        long b,prf_sum,suf_sum;
        pair2(int a,long b){
            this.a=a;
            this.b=b;
        }
    }

    static void diji(int s, long dist[], ArrayList<pair> adj[]) {
        dist[s] = 0;
        PriorityQueue<pair> q = new PriorityQueue<>(new cmp());
        q.add(new pair(s, 0));
        while (!q.isEmpty()) {
            pair p1 = q.poll();
            for (pair ne: adj[p1.a]) {

                if ((long) p1.b + (long) ne.b < dist[ne.a]) {
                    dist[ne.a] = (long) p1.b + (long) ne.b;
                    pair p2 = new pair(ne.a, dist[ne.a]);
                    q.add(p2);

                }

            }
        }

    }
    static class cmp implements Comparator<pair>{

        public  int compare(pair o1,pair o2)
        {
            return o1.b<o2.b?-1:o1.b>o2.b?1:0;
        }

    }

    static class pair {
        int a;
        long b;
        pair(int a,long b){
            this.a=a;
            this.b=b;
        }
        public boolean equals(Object obj) {      //  override equals method for object to remove tem from arraylist and sets etc.......
            if (this == obj)
                return true;
            if (obj == null)
                return false;
            if (getClass() != obj.getClass())
                return false;
            pair other = (pair) obj;
            if (b!= other.b||a!=other.a)
                return false;
            return true;
        }
    }

    static long modinv(long a,long b)
    {
        long p=power(b,mod-2);

        p=a%mod*p%mod;
        p%=mod;

        return p;

    }

    static long power(long x,long y){
        if(y==0)return 1%mod;
        if(y==1)return x%mod;


        long res=1;
        x=x%mod;
        while(y>0){


            if((y%2)!=0){
                res=(res*x)%mod;
            }


            y=y/2;
            x=(x*x)%mod;
        }


        return res;

    }
    static  long gcd(long a,long b){

        if(b==0)return a;
        return gcd(b,a%b);
    }

    static  void sev(int a[],int n){

        for(int i=2;i<=n;i++)a[i]=i;
        for(int i=2;i<=n;i++){

            if(a[i]!=0){
                for(int j=2*i;j<=n;){

                    a[j]=0;
                    j=j+i;
                }
            }

        }

    }



    static class InputReader
    {
        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 String nextLine()
        {
            BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
            String str = "";
            try
            {
                str = br.readLine();
            }
            catch (IOException e)
            {
                e.printStackTrace();
            }
            return str;
        }
        public int nextInt()
        {
            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 nextLong()
        {
            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 double nextDouble()
        {
            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, nextInt());
                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, nextInt());
                    if (c < '0' || c > '9')
                        throw new InputMismatchException();
                    m /= 10;
                    res += (c - '0') * m;
                    c = read();
                }
            }
            return res * sgn;
        }

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

            return res.toString();
        }

        public boolean isSpaceChar(int c)
        {
            if (filter != null)
                return filter.isSpaceChar(c);
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }

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

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