#include<bits/stdc++.h>
#define f(s,f,p) for(int i=(s);i<=(f);i+=(p)) 
using namespace std;
map<int,int> f;
void make_family(int n){
	f(1,n,1){
		f[i]=i;
	}
}
int parentof(int n){
	if(n==f[n]){
		return n;
	}
	return parentof(f[n]);
}
void join_family(int n,int m){
	f[parentof(n)]=parentof(m);
}
int main(){
    int n,m,t1,t2,ans;
    f(1,2,-1){
    	ans=0;
    	cin>>n;
        if(!n){
            break;
        }
        make_family(n);
        cin>>m;
        f(1,m,1){
        	cin>>t1>>t2;
        	join_family(t1,t2);
		}
		f(1,n,1){
			if(i==parentof(i)){
				ans++;
			}
		}
		cout<<ans-1<<endl;
	}
    return 0;
}