#include <bits/stdc++.h>
#include <atcoder/all>
using mint = atcoder::modint998244353;
// using mint = atcoder::modint1000000007;
using namespace atcoder;
using namespace std;

#define rep(i,n) for (int i = 0; i < n; i++)
using ll = long long;
set<char> abc = {'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'};
const int inf =1e9;
const ll infl = 4e18;
template <typename T>
bool chmax(T &a, const T& b) {if (a < b) {a = b;  return true;}return false;}
template <typename T>
bool chmin(T &a, const T& b) {if (a > b) {a = b;  return true;}return false;}


int main(){
    int N,M; cin >> N >> M;
    vector<ll> A(N);rep(i,N) cin >> A[i];
    vector<vector<pair<int,ll>>> G(N);
    rep(i,M){
        int a,b; ll c; cin >> a >> b >> c;
        a--;b--;
        G[a].emplace_back(b,A[b]-c);
    }
    vector<ll> dist(N,-infl);
    dist[0]=A[0];
    rep(i,N-1){
        rep(j,N){
            if(dist[j]==-infl) continue;
            for(auto p:G[j]){
                if(dist[p.first]<dist[j]+p.second) dist[p.first]=dist[j]+p.second;
            }
        }
    }
    rep(i,N){
        rep(j,N){
            if(dist[j]==-infl) continue;
            for(auto p:G[j]){
                if(dist[p.first]<dist[j]+p.second && p.first==N-1){
                    cout << "inf" << endl;
                    return 0;
                }
                if (dist[p.first]<dist[j]+p.second) dist[p.first]=dist[j]+p.second;
            }
        }
    }
    cout << dist[N-1] << endl;
}