#include <iostream>
#include <fstream>

using namespace std;

ifstream fin("dfs.in");
ofstream fout("dfs.out");

int main() {
    int n,m;
    int a,b;
    int k;

    fin >> n >> m;
    int S=0;
    int v[n+1];
    for (int i = 0; i <= n; ++i) {
        v[i]=i;
    }
    for (int j = 0; j < m; ++j) {
        fin >> a >> b;
        k=v[a];
        for (int i = 1; i <= n; ++i) {
            if(v[i]==k){v[i]=b;
            //igz=true;
            }
        }
       // if(igz==true)S--;
    }
    for (int i = 1; i <= n; ++i) {
        if(v[i]!=0){S++;
            for (int j = i+1; j <= n; ++j) {
                if(v[j]==v[i])v[j]=0;
            }
        v[i]=0;
        }
    }
    fout << S;
}