#include <bits/stdc++.h>
#define NMAX 100000 +5

using namespace std;
FILE *in, *out;

int nr_noduri, nr_muchii;

vector<int> muchii[NMAX];
bool parcurs[NMAX];

void read() {
    in = fopen("dfs.in", "r");

    fscanf(in, "%d %d", &nr_noduri, &nr_muchii);
    for(int i = 1; i <= nr_muchii; ++i) {
        int x, y;
        fscanf(in, "%d %d", &x, &y);

        muchii[x].push_back(y);
        muchii[y].push_back(x);
    }
    fclose(in);
}

void DFS() {
    for(int i = 1; i <= nr_noduri; ++i) {
        if(!parcurs[i]) {
            for(auto it = muchii[i].begin(); it != muchii[i].end(); ++it)
                parcurs[*it] = 1;
        }
    }
}

int main()
{
    read();
    DFS();

    int comp_conexe = 0;
    for(int i = 1; i <= nr_noduri; ++i)
        if(!parcurs[i])
            ++comp_conexe;

    out = fopen("dfs.out", "w");
    fprintf(out, "%d", comp_conexe);
    fclose(out);
    return 0;
}