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

using namespace std;

const int N = 100010, M = N * 2;

int h[N], e[M], ne[M], idx;

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

int main() {
    memset(h, -1, sizeof h);
}