#include <bits/stdc++.h>
using namespace std;
const int MAXN=100005;
int n,m;
vector<int> G[MAXN];//试一下动态存图
int dfn[MAXN],low[MAXN],cnt=0,index_=0;
int scc[MAXN],size[MAXN];
bool inStack[MAXN];
stack<int> st;
void tarjan(int u)
{
    index_++;
    dfn[u]=index_;
    low[u]=index_;
    st.push(u);
    inStack[u]=true;
    for(int i=0;i<G[u].size();i++)
    {
        if(!dfn[G[u][i]])
        {
            tarjan(G[u][i]);
            low[u]=min(low[u],low[G[u][i]]);
        }
        else if(inStack[G[u][i]])
            low[u]=min(low[u],dfn[G[u][i]]);
    }
    if(low[u]==dfn[u])
    {
        cnt++;
        while(st.top()!=u)
        {
            scc[st.top()]=cnt;
            size[cnt]++;
            inStack[st.top()]=false;
            st.pop();
        }
        scc[st.top()]=cnt;
        size[cnt]++;
        inStack[st.top()]=false;
        st.pop();
    }
}
inline void clear()
{
    for(int i=0;i<=MAXN;i++)
    G[i].clear();
    cnt=0;
    memset(scc,0,sizeof(scc));
    memset(inStack,0,sizeof(inStack));
    memset(size,0,sizeof(size));
    memset(low,0,sizeof(low));
    memset(dfn,0,sizeof(dfn));
    while( !st.empty() )
      st.pop();
    index_=0;
}
int main()
{
    ios::sync_with_stdio(0);   //syn加速
    for(;;)
    {
        clear();
        cin>>n;
        if(n==0) break;
        cin>>m;
        for(int i=0;i<m;i++)
           {
            int x,y;
            cin>>x>>y;
            G[x].push_back(y);
            G[y].push_back(x);
        }
        for(int i=1;i<=n;i++)
            if(!dfn[i])
                tarjan(i);
        cout<<cnt-1<<endl;        
    }
return 0;
}