#include <cstdio>
#include <vector>
#include <stack>

#define NMax 100005
using namespace std;

int n,m,x,y,k;
int viz[NMax];
stack<int> s;
vector<int> vecini[NMax];

void dfs(int k){
    s.push(k);
    while(!s.empty()){
        int nod = s.top();
        s.pop();
        viz[nod] = 1;
        for(int i = 0; i < vecini[nod].size(); ++i){
            if(!viz[vecini[nod][i]]){
                s.push(vecini[nod][i]);
            }
        }
    }
}
int main()
{
    freopen("dfs.in","r",stdin);
    freopen("dfs.out","w",stdout);
    scanf("%d%d",&n,&m);
    for(int i = 1; i <= m; ++i){
        scanf("%d%d",&x,&y);
        vecini[x].push_back(y);
        vecini[y].push_back(x);
    }
    int ok = 1;
    while(ok){
        ok = 0;
        for(int i = 1; i <= n; ++i){
            if(!viz[i]){
                dfs(i);
                ok = 1;
                k++;
                break;
            }
        }
    }
    printf("%d ",k);
    return 0;
}