#include<bits/stdc++.h>
using namespace std;

//* ATCODER
#include<atcoder/all>
using namespace atcoder;
typedef modint998244353 mint;
//*/

/* BOOST MULTIPRECISION
#include<boost/multiprecision/cpp_int.hpp>
using namespace boost::multiprecision;
//*/

typedef long long ll;

#define rep(i, s, n) for (int i = (int)(s); i < (int)(n); i++)
#define rrep(i, s, n) for (int i = (int)(n)-1; i >= (int)(s); i--)

template <typename T> bool chmin(T &a, const T &b) {
	if (a <= b) return false;
	a = b;
	return true;
}

template <typename T> bool chmax(T &a, const T &b) {
	if (a >= b) return false;
	a = b;
	return true;
}

template <typename T> T max(vector<T> &a){
	assert(!a.empty());
	T ret = a[0];
	for (int i=0; i<(int)a.size(); i++) chmax(ret, a[i]);
	return ret;
}

template <typename T> T min(vector<T> &a){
	assert(!a.empty());
	T ret = a[0];
	for (int i=0; i<(int)a.size(); i++) chmin(ret, a[i]);
	return ret;
}

template <typename T> T sum(vector<T> &a){
	T ret = 0;
	for (int i=0; i<(int)a.size(); i++) ret += a[i];
	return ret;
}


int main(){
	int n, m; cin >> n >> m;
	vector<ll> a(n);
	rep(i,0,n) cin >> a[i];
	
	vector<int> u(m), v(m);
	vector<ll> c(m);
	rep(i,0,m){
		cin >> u[i] >> v[i];
		u[i]--;
		v[i]--;
		cin >> c[i];
		c[i] -= a[v[i]];
	}

	vector<ll> d1(n,1e18);
	d1[n-1] = 0;
	rep(i,0,n){
		rep(j,0,m){
			chmin(d1[u[j]], d1[v[j]]);
		}
	}

	vector<ll> d2(n,1e18);
	d2[0] = 0;
	bool mode = 1;
	rep(i,0,n+1){
		rep(j,0,m){
			if (d1[u[j]] == 0 || d1[v[j]] == 0){
				if (chmin(d2[v[j]], d2[u[j]] + c[j]) && i == n){
					mode = 0;
				}
			}
		}
	}

	if (!mode){
		cout << "inf" << '\n';
		return 0;
	}

	vector<ll> d(n,1e18);
	d[0] = -a[0];
	rep(i,0,n){
		rep(j,0,m){
			chmin(d[v[j]], d[u[j]] + c[j]);
		}
	}
	cout << - d[n-1] << '\n';
}