#include <cstdio>
#include <cstring>
#include <algorithm>
#include <map>
#include <queue>
#define MP(a, b) make_pair(a, b)
using namespace std;
const int MAXN = 1000 + 5;
const int INF = 0x3f3f3f3f;
 
int pa[MAXN];
 
int Find(int x)
{
    return pa[x] == x ? x : pa[x] = Find(pa[x]);
}
 
int main()
{
    //freopen("input.txt", "r", stdin);
    int nc, nr, i, j, a, b;
    while (scanf("%d", &nc), nc)
    {
        for (i = 1; i <= nc; i++)
            pa[i] = i;
        int cnt = -1;
        scanf("%d", &nr);
        for (i = 0; i < nr; i++)
        {
            scanf("%d%d", &a, &b);
            int x = Find(a), y = Find(b);
            if (x != y)
                pa[x] = y;
        }
        for (i = 1; i <= nc; i++)
            if (pa[i] == i) cnt++;
        printf("%d\n", cnt);
    }
    return 0;
}