#include using namespace std; using ll =int; #define all(v) v.begin(),v.end() #define rep(i,a,b) for(int i=a;i=b;i--) vector>> vec; vector del; vector this_sec; vector check; vector check_edge; ll dfs(ll now) { if(this_sec[now]) { return now; } if(check[now]) return -1; this_sec[now]=true; vector> no; for(auto x:vec[now]) { no.push_back(x); ll k=dfs(x.first); if(k>=0) { del[x.second]=true; if(k!=now) { for(auto y:no) vec[now].erase(y); this_sec[now]=false; return k; } } else check_edge[x.second]=true; } for(auto y:no) vec[now].erase(y); check[now]=true; this_sec[now]=false; return -1LL; } int main() { ios::sync_with_stdio(false); cin.tie(0); ll N,M;cin>>N>>M; vec=vector>> (N+100); del=vector (M+100); check=vector (N+100); check_edge=vector (M+100); this_sec=vector (N+100); vector> memo(M); for(ll i=0;i>U>>V; U--;V--; vec[U].insert(make_pair(V,i)); memo[i]=make_tuple(U,V,i); } for(ll i=0;i> ans(0); for(auto x:memo) { if(del[get<2>(x)]) continue; ans.push_back(make_pair(get<0>(x),get<1>(x))); } cout<