#include<bits/stdc++.h> usingnamespace std; #define ll long long constint INF = 0x3f3f3f3f; const ll inf = 0x3f3f3f3f3f3f3f3f; const ll mod = 1e9 + 7; constint N = 2e5 + 10; int T; vector<int>G[N], ans; int co[N]; intmain(){ scanf("%d", &T); while (T--) { int n, m; scanf("%d%d", &n, &m); for (int i = 1; i <= n; i++)G[i].clear(); ans.clear(); fill(co, co + n + 1, 0); for (int i = 0; i < m; i++) { int u, v; scanf("%d%d", &u, &v); G[u].push_back(v); } for (int i = 1; i <= n; i++) { if (co[i] == 2)ans.push_back(i); else { for (int v : G[i]) { co[v] = max(co[v], co[i] + 1); } } } printf("%d\n", (int)ans.size()); for (int u : ans)printf("%d ", u); puts(""); } return0; }