#include "swap.h"
#include <bits/stdc++.h>
#define rep(i, n) for(ll i = 0; i < ll(n); i++)
#define rep2(i, s, n) for(ll i = ll(s); i < ll(n); i++)
#define all(a) a.begin(),a.end()
#define rall(a) a.rbegin(),a.rend()
#define pb push_back
#define eb emplace_back
using namespace std;
using ll = long long;
using P = pair<int, int>;
using vi = vector<int>;
using vvi = vector<vi>;
using vl = vector<ll>;
using vvl = vector<vl>;
using vp = vector<P>;
using vvp = vector<vp>;
using vb = vector<bool>;
using vvb = vector<vb>;
template<class T>
bool chmin(T &a, T b) {
if (a > b) {
a = b;
return true;
}
return false;
}
template<class T>
bool chmax(T &a, T b) {
if (a < b) {
a = b;
return true;
}
return false;
}
const int inf = 1001001001;
namespace {
int n;
vvp G;
vi deg;
int mx;
bool cycle;
}
void init(int _n, int m, vi u, vi v, vi w) {
n = _n;
G.resize(n);
deg.resize(n);
mx = 0;
rep(i, m) {
G[u[i]].eb(v[i], w[i]);
G[v[i]].eb(u[i], w[i]);
deg[u[i]]++;
deg[v[i]]++;
chmax(mx, w[i]);
}
cycle = true;
rep(i, n) cycle &= deg[i] == 2;
}
int getMinimumFuelCapacity(int x, int y) {
return (cycle ? mx : -1);
}
