#include "bits/stdc++.h"

#include <stdio.h>
#include <math.h>

#include "atcoder/all"
#include <float.h>

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

using namespace std;
using namespace atcoder;

#ifdef _MSVC_LANG
// no getchar_unlocked on Windows so just call getchar
inline int getchar_unlocked() { return getchar(); }
#endif

using ll = long long;
using ull = unsigned long long;
using mint = modint998244353;
using mint2 = modint1000000007;

const double eps = 1e-9;

#define REP(i, n) for (ll i = 0; i < ll(n); ++i)
#define REPI(i, init, n) for (ll i = init; i < ll(n); ++i)
#define REPD(i, init) for (ll i = init; i >=0; --i)
#define REPDI(i, init, n) for (ll i = init; i >=n; --i)
#define REPE(i, c) for (const auto& i : c)
#define TCASE() ll _ttt; cin >> _ttt; while(_ttt--)

using vl = vector<ll>; using vvl = vector<vl>; using vvvl = vector<vvl>;
#define VL(a, n) vector<ll> a; a.assign(n, 0);
#define VLI(a, n) vector<ll> a; a.assign(n, 0); for(auto& x : a) cin >> x;
#define VSI(a, n) vector<string> a; a.assign(n, ""); for(auto& x : a) cin >> x;
#define VVLI(a, n, m, init) vector<vector<ll>> a(n); for(auto& x : a) x.assign(m, init);
using vd = vector<double>;
using pl = pair<ll, ll>;

struct uv { ll u; ll v; ll c; };
#define VUVI(a, n) vector<uv> a; a.assign(n, {0, 0, 1}); for(auto& x : a) {cin >> x.u >> x.v; x.u--; x.v--;}
#define VUVCI(a, n) vector<uv> a; a.assign(n, {0, 0, 0}); for(auto& x : a) {cin >> x.u >> x.v >> x.c; x.u--; x.v--;}
vvl to_edge(const ll n, const vector<uv>& v) { vvl ret(n); for (auto& x : v) ret[x.u].push_back(x.v); return ret; }
vvl to_edge_d(const ll n, const vector<uv>& v) { vvl ret(n); for (auto& x : v) { ret[x.u].push_back(x.v); ret[x.v].push_back(x.u); } return ret; }

template <class T = long long> using pql = priority_queue<T>;
template <class T = long long> using pqg = priority_queue<T, vector<T>, greater<T>>;
using vm = vector<mint>; using vvm = vector<vm>;

ostream& operator<<(ostream& os, const mint& v) { os << v.val(); return os; }
void yn(bool f) { std::cout << (f ? "Yes" : "No") << endl; };
template<class T> void ov(const T& v) { for (auto it = v.begin(); it != v.end(); it++) { if (it != v.begin()) cout << " "; cout << *it; } };
template<> void ov(const vm& v) { for (auto it = v.begin(); it != v.end(); it++) { if (it != v.begin()) cout << " "; cout << it->val(); } };

const ll llhuge = 1LL << 62; //十分でかいが多少足しても溢れない数値
auto gmax(const auto& a, const auto& b) { return a > b ? a : b; };
auto gmin(const auto& a, const auto& b) { return a < b ? a : b; };
bool chmin(auto& a, const auto& b) { const auto olda = a; a = gmin(a, b); return olda != a; }
bool chmax(auto& a, const auto& b) { const auto olda = a; a = gmax(a, b); return olda != a; }
template<class T> void mysort(T& v) { std::sort(begin(v), end(v)); };
template<class T, class U> void mysort(T& v, U pr) { std::sort(begin(v), end(v), pr); };
template<class T> void myrev(T& v) { std::reverse(begin(v), end(v)); };
template<class T, class K = T::key_type, class V = T::mapped_type> [[nodiscard]] V myat(const T& mp, const K& key) { return mp.find(key) == mp.end() ? V() : mp.at(key); }
long long ceil(const long long a, const long long b) { return (a + b - 1) / b; }

vl d;

//ベルマンフォード
//戻り値がtrueなら負の閉路が存在する
//dには最短距離が入る
bool bellman_ford(const ll n, const vector<uv>& v, const vector<bool>& reach) {
	d.assign(n, llhuge);
	d[0] = 0;
	REP(i, n) {
		REPE(x, v) {
			if (!reach[x.u] || !reach[x.v]) continue;
			if (d[x.u] == llhuge) continue;
			if (d[x.v] > d[x.u] + x.c) {
				d[x.v] = d[x.u] + x.c;
				if (i == n - 1) return true;
			}
		}
	}
	return false;
}

int main() {
	cin.tie(nullptr);
	ios::sync_with_stdio(false);

	ll n, m;
	cin >> n >> m;
	VLI(ai, n);

	vvl gd(n);
	vector<uv> g;
	REP(i, m) {
		ll a, b, c;
		cin >> a >> b >> c;
		a--; b--;
		g.push_back({ a, b, c - ai[b]});
		
		gd[b].push_back(a);
	}

	//到達可能性チェック
	vector<bool> reach(n, false);
	queue<ll> q;
	q.push(n - 1);
	while (!q.empty()) {
		ll x = q.front();
		q.pop();
		if (reach[x]) continue;
		reach[x] = true;
		REPE(y, gd[x]) q.push(y);
	}
	
	bool loop = bellman_ford(n, g, reach);
	if (loop) cout << "inf" << endl;
	else cout << -d[n - 1] + ai[0] << endl;
}