#include<cstdio>
#include<vector>
#include<queue>
using namespace std;

FILE* in=fopen("dfs.in", "r");
FILE* out=fopen("dfs.out", "w");
vector<int> vecini[200007];
queue<int> q;
bool v[100007];

void dfs(int nod)
{
    v[nod]=true;
    q.pop();
    for(int i=0; i<vecini[nod].size(); ++i)
    {
        if(!v[vecini[nod][i]]) q.push(vecini[nod][i]);
    }
    if(!q.empty())
    {
        dfs(q.front());
    }
}

int main()
{
    int n, m;
    fscanf(in, "%d%d", &n, &m);
    for(int i=1; i<=m; ++i)
    {
        int x, y;
        fscanf(in, "%d%d", &x, &y);
        vecini[x].push_back(y);
        vecini[y].push_back(x);
    }

    int ct=0;
    for(int i=1; i<=n; ++i)
    {
        if(!v[i])
        {
            q.push(i);
            dfs(i);
            ++ct;
        }
    }
    fprintf(out, "%d", ct);
}