#include<cstring>
#include<iostream>
#include<algorithm>

using namespace std;

const int N = 1e5 + 10, M = N * 2;

int h[N],e[M],ne[M],idx;
bool st[N];
void add(int a,int b){
    e[idx] = b;
    ne[idx] = h[a];
    h[a] = idx++;
}

void dfs(int u){

    st[u] = true;

    for(int i = h[u];i != -1;i = ne[i]){
        int j = e[i];
        if(!st[j]) dfs(j);
    }
}

int main(){

    memset(h,-1,sizeof h);

    return 0;
}