#include<cstdio>
#include<cstring>
#include<vector>
#include<algorithm>
using namespace std;
const int N = 1005;vector<int>mp[N];
vector<int>cut[N];
int G[N][N],low[N],dfn[N],stack[N],mark[N],color[N];
int m,n,cnt,stack_ptr,cut_num,flag;
void DFS(int x, int father)
{low[x] = dfn[x] = ++cnt;stack[stack_ptr++] = x;int len = mp[x].size();for (int i = 0; i < len; i++){int t = mp[x][i];if (!dfn[t]){DFS(t,x);low[x] = min(low[x], low[t]);if (dfn[x] <= low[t]) {cut[cut_num].push_back(x);        while (stack[stack_ptr-1] != t)cut[cut_num].push_back(stack[--stack_ptr]);cut[cut_num++].push_back(stack[--stack_ptr]);}}else if (t != father)low[x] = min(low[x], dfn[t]);}
}
void check(int x, int d, int col,int fa)
{color[x] = col;int len = mp[x].size();for (int i = 0; i < len; i++){int t = mp[x][i];if (t == fa) continue;vector<int>::iterator it = find(cut[d].begin(),cut[d].end(),t);if (it != cut[d].end())if (color[t] == 0)check(t,d,-col,x);else if (color[t] == col)flag = 1;}
}
int Tarjan()
{memset(low,0,sizeof(low));memset(dfn,0,sizeof(dfn));memset(cut,0,sizeof(cut));cnt = stack_ptr = cut_num = 0;for (int i = 1; i <= n; i++)if (!dfn[i])DFS(i,-1);memset(mark,0,sizeof(mark));for (int i = 0; i < cut_num; i++){memset(color,0,sizeof(color));int len = cut[i].size();flag = 0;if(len >= 3){check(cut[i][0],i,1,-1);if (flag)for (int j = 0; j < len; j++)mark[cut[i][j]] = 1;}}int ans = 0;for (int i = 1; i <= n; i++)if (!mark[i])ans++;return ans;
}
int main()
{while (scanf("%d%d",&n,&m) && n+m){int a,b;for (int i = 0; i <= n; i++){mp[i].clear();cut[i].clear();}memset(G,0,sizeof(G));while (m--){scanf("%d%d",&a,&b);G[a][b] = G[b][a] = 1;}for (int i = 1; i <= n; i++)for (int j = 1; j <= n; j++)if (i!=j && G[i][j]==0)mp[i].push_back(j);printf("%d\n",Tarjan());}return 0;
}