#include <bits/stdc++.h>
using namespace std;
using ll=long long;
using ld=long double;
template<class T> using graph=vector<vector<T>>;
template<class T> using min_priority_queue=priority_queue<T,vector<T>,greater<T>>;
constexpr int INF32=INT_MAX/2;
constexpr ll INF64=1LL<<60;
constexpr array<int,4> DX4={0,1,0,-1};
constexpr array<int,4> DY4={-1,0,1,0};
constexpr array<int,8> DX8={0,1,1,1,0,-1,-1,-1};
constexpr array<int,8> DY8={-1,-1,0,1,1,1,0,-1};
inline int popcnt(ll n){return __builtin_popcountll(n);}
template<class T> inline bool chmax(T& a,const T& b){return a<b?a=b,true:false;}
template<class T> inline bool chmin(T& a,const T& b){return b<a?a=b,true:false;}
#define rep(i,s,n) for(ll i=(ll)(s);i<(ll)(n);i++)
#define rrep(i,s,n) for(ll i=(ll)(s);i>=(ll)(n);i--)
void _main();
int main(){
	cin.tie(nullptr);
	ios_base::sync_with_stdio(false);
	cout<<fixed<<setprecision(16);
	_main();
}

void _main(){
	int N, M; cin >> N >> M;
	vector<ll> A(N); rep(i,0,N) cin >> A[i];
	vector<tuple<int,int,ll>> edge;
	rep(i,0,M){
		int a, b; cin >> a >> b; a--; b--;
		ll c; cin >> c;
		edge.emplace_back(a, b, c-A[b]);
	}

	bool inf = true;
	vector<ll> dist(N, INF64);
	dist[0] = 0;
	rep(i,0,N){
		bool ok = true;
		for(auto [v, nv, c]:edge){
			if(dist[v]==INF64) continue;
			ll nd = dist[v]+c;
			if(chmin(dist[nv], nd)) ok = false;
		}
		if(ok){
			inf = false;
			break;
		}
	}

	if(inf) cout << "inf" << endl;
	else cout << A[0]-dist[N-1] << endl;
}