ctc_impar

#include <iostream>

using namespace std;
int n, m, a[105][105], ctc[105], s[105], p[105], nrc, sol;
void df1(int x)
{
    s[x] = 1;
    for(int i =1 ; i <= n ; i ++)
        if(s[i] == 0 && a[x][i] == 1)
            df1(i);
}

void df2(int x)
{
    p[x] = 1;
    for(int i =1 ; i <= n ; i ++)
        if(p[i] == 0 && a[i][x] == 1)
            df2(i);
}
int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    int i, j;
    cin>>n>>m;
    while(m)
    {
        cin>>i>>j;
        a[i][j]=1;
        m --;
    }
    for(int i = 1 ; i <= n ; ++i)
        if(ctc[i] == 0)
        {
            for(int j = 1; j <= n ; ++j)
                s[j] = p[j] = 0;
            nrc ++;
            df1(i);
            df2(i);
            for(int j = 1; j <= n ; ++j)
                if(s[j] == 1 && p[j] == 1)
                    ctc[j] = nrc;
        }
    for(int i =1 ; i <= nrc ; ++i)
    {
        int cnt=0;
        for(int j =1 ; j <= n ; ++j)
            if(ctc[j] == i)
                cnt++;
        if(cnt%2)
            sol++;
    }
    cout<<sol;
    return 0;
}