tyvj2059 元芳看电影

#include<iostream>
#include<cstdio>
#include<string>
#include<cstring>
#include<algorithm>
#include<vector>
using namespace std;
const int maxn = 105;
const int maxint = 100000000;
int n,m,g[maxn][maxn],tg[maxn][maxn],ans,nowans;
void input(){
    cin>>n>>m;
    int u,v;
    for(int i = 1;i <= m;i++){
        cin>>u>>v;
        g[u][v] = 1;
    }
}
void build(){
    for(int k = 1;k <= n;k++){
        for(int i = 1;i <= n;i++){
            for(int j = 1;j <= n;j++){
                if(k != i && k != j && i != j) g[i][j] = g[i][j] || (g[i][k] && g[k][j]);
            }
        }
    }
    for(int i = 1;i <= n;i++){
        nowans = 0;
        for(int j = 1;j <= n;j++){
            if(g[i][j]) nowans++;
            if(g[j][i]) nowans++;
        }
        if(nowans == n-1) ans++;
    }
    cout<<ans<<endl;
}
int main(){
    input();
    build();
}