#include<bits/stdc++.h>
using namespace std;
ifstream F("dfs.in");
ofstream G("dfs.out");
int n,i,x,c;
vector<int> v[100001];
bool z[100001];
void D(int x)
{
    z[x]=1;
    for(auto y:v[x])
        if(!z[y])
            D(y);
}
int main()
{
    for(F>>n>>x;F>>x>>i;v[x].push_back(i),v[i].push_back(x));
    for(i=1;i<=n;++i)
        if(!z[i])
            ++c,D(i);
    return G<<c,0;
}