#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].push_back({b,A[b]-c});
    }
    vector<ll> dp(N,-infl);
    dp[0]=A[0];
    rep(i,2*N){
        vector<ll> dp2;
        dp2=dp;
        rep(j,N){
            for (auto e:G[j]){
                if (dp[j]==-infl) continue;
                if (i>=N && e.first==N-1){
                    if (dp2[e.first]<dp[j]+e.second){
                        cout << "inf" << endl;
                        return 0;
                    }
                }
                chmax(dp2[e.first],dp[j]+e.second);
            }
        }
        swap(dp,dp2);
    }
    cout << dp[N-1] << endl;
}