// #pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h>
using namespace std;
#include <atcoder/all>
using namespace atcoder;
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>
#include<ext/pb_ds/tag_and_trait.hpp>
using namespace __gnu_pbds;

#define ALL(a) (a).begin(), (a).end()
#define RALL(a) (a).rbegin(), (a).rend()
#define FOR(i, start, end) for (int i = start; i < (int)(end); ++i)
#define RFOR(i, rstart, rend) for (int i = rstart; i >= (int)(rend); --i)
#define REP(i, end) FOR(i, 0, end)
#define BIT(x, i) (((x)>>(i))&1)
using ll = long long;
using ull = unsigned long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
constexpr ll LINF = 1LL << 60;
constexpr int INF = 1 << 30;
template <typename T> using Graph = vector<vector<T>>;
template <typename T> using TREE = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
template <typename T> using PQ = priority_queue<T, vector<T>, greater<T>>;
void yes(bool expr) {cout << (expr ? "Yes" : "No") << "\n";}
template<typename T>void chmax(T &a, const T &b) { if (a<b) a=b; }
template<typename T>void chmin(T &a, const T &b) { if (b<a) a=b; }
template<typename T> istream &operator>>(istream&is,vector<T>&v){for(T &in:v){is>>in;}return is;}
template<typename T> ostream &operator<<(ostream&os,const vector<T>&v){for(auto it=v.begin();it!=v.end();){os<<*it<<((++it)!=v.end()?" ":"\n");}return os;}
/* 回文判定 */ bool isPalindrome(const string &s){int sz=s.size(); REP(i,sz/2){if(s[i]!=s[sz-1-i])return false;} return true;}
/* 座標圧縮 */ template<typename T> vector<int> compress(const vector<T>&A){vector<int> ret(A.size()); auto tmp = A; sort(ALL(tmp)); tmp.erase(unique(ALL(tmp)), tmp.end()); REP(i,A.size()) ret[i] = lower_bound(ALL(tmp), A[i]) - tmp.begin(); return ret;}
/* 約数列挙　整数nの約数のvectorを返す */ vector<ll> enumdiv(ll n){vector<ll>s; for(ll i = 1;i*i<=n;i++){if(n%i==0){s.push_back(i);if(i*i!=n)s.push_back(n/i);}}return s;}
/* 素因数分解 pair<素数、指数>のvectorを返す */ vector<pll> primeDecomposition(ll x){vector<pll> ret;ll tmp=x;for(ll i=2;i*i<=x;++i){if(tmp%i==0){ll cnt=0; while(tmp%i==0){tmp/=i;++cnt;}ret.emplace_back(i,cnt);}}if(tmp!=1)ret.emplace_back(tmp,1);return ret;}
/* エラトステネスの篩　n未満の素数を列挙。isprimeには素数かどうかが入っている */ vector<bool> isprime;vector<int> era(int n) {isprime.resize(n, true);vector<int> res;isprime[0] = false; isprime[1] = false;for (int i = 2; i < n; ++i){if (isprime[i]) {res.push_back(i);for (int j = i*2; j < n; j += i) isprime[j] = false;}}return res;}
/* トポロジカルソート */ vector<int> topo_sort(const Graph<int> &G){int n = G.size();vector<int> deg(n), ret;for(const auto &v:G)for(const auto &to:v) ++deg[to];queue<int> que;REP(i,n) if(deg[i]==0)que.push(i);while(!que.empty()){const int from = que.front();que.pop();ret.push_back(from);for(const auto &to:G[from])if(--deg[to]==0) que.push(to);}return ret;};
using mint = modint998244353;
// using mint = modint;

int main()
{
	ios::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);

	int n,m;
	cin >> n >> m;
	vector<ll> a(n);
	cin >> a;
	vector<int> U(m),V(m);
	vector<ll> C(m);
	REP(i,m){
		cin >> U[i] >> V[i] >> C[i];
		--U[i];--V[i];
		C[i] = a[V[i]] - C[i];
		C[i] *= -1;
	}


	vector<ll> dist(n,LINF);
	dist[0] = 0;
	REP(i,n){
		REP(j,m){
			int u = U[j];
			int v = V[j];
			ll c = C[j];
			if(dist[v] > dist[u] + c){
				dist[v] = dist[u] + c;
				if(i==n-1){
					cout << "inf" << endl;
					return 0;
				}
			}
		}
	}

	ll ans = -dist[n-1] + a[0];
	cout << ans << endl;

	return 0;
}