#include <bits/stdc++.h>

using namespace std;

int n, m, x, y, k;
bool a[4000][4000];
int viz[4000];

void bfs(int in) {
    viz[in] = k;
    queue<int> q;
    q.push(in);
    while(!q.empty()) {
        in = q.front();
        q.pop();
        for(int i = 1; i <= n; i ++) {
            if(a[in][i] && !viz[i]) {
                viz[i] = k;
                q.push(i);
            }
        }
    }
}

int main()
{
    FILE *f = fopen("dfs.in", "r");
    FILE *g = fopen("dfs.out", "w");
    fscanf(f, "%d %d", &n, &m);
    for(int i = 1; i <= m; i ++) {
        fscanf(f, "%d %d", &x, &y);
        a[x][y] = true;
        a[y][x] = true;
    }
    for(int i = 1; i <= n; i ++) {
        if(!viz[i]) {
            k ++;
            bfs(i);
        }
    }
    fprintf(g, "%d\n", k);
    return 0;
}