#include <cstdio>
#include <vector>
#define DIM 100005
#define pb push_back
using namespace std;

vector <int> A[DIM], v;
int n, m, count;

void DFS(int start)
{
    v[start] = 1;


    for (int i = 1; i <= A[start][0]; i++)
        if (!v[A[start][i]])
        {
            count++;
            DFS(A[start][i]);
        }
}

int main()
{
    FILE *f = fopen("dfs.in", "r");
    fscanf(f, "%d%d", &n, &m);

    int i, x, y;
    for (i = 1; i <= n; i++)
        A[i].pb(0), v.pb(0);

    for (i = 1; i <= m; i++)
    {
        fscanf(f, "%d%d", &x, &y);
        A[x].pb(y);
        A[x][0]++;

        A[y].pb(x);
        A[y][0]++;

    }

    fclose(f);

    for (i = 1; i <= n; i++)
        if (!v[i])
            DFS(i);
/*
    for (i = 1; i <= n; i++)
    {
        for (int j = 1; j <= A[i][0]; j++)
            printf("%d ", A[i][j]);

        printf("\n");
    }
*/

    f = fopen("dfs.out", "w");
    fprintf(f, "%d\n", count);
    fclose(f);

    return 0;
}