#include <iostream>#include <cstdio>#include <cstdlib>#include <cstring>using namespace std;#define maxn 106int n, m;bool g[maxn][maxn];int main(){ scanf("%d%d", &n, &m); memset(g, 0, sizeof(g)); for (int i = 0; i < m; i++) { int a, b; scanf("%d%d", &a, &b); g[a][b] = true; } for (int i = 1; i <= n; i++) for (int j = 1; j <= n; j++) for (int k = 1; k <= n; k++) if (g[j][i] && g[i][k]) g[j][k] = true; int ans = 0; for (int i = 1; i <= n; i++) { int temp = 0; for (int j = 1; j <= n; j++) temp += g[i][j] + g[j][i]; if (temp == n - 1) ans++; } printf("%dn", ans); return 0;}
