#include<bits/stdc++.h>
#include<atcoder/all>
#define chmin(x,y) (x) = min((x),(y))
#define chmax(x,y) (x) = max((x),(y))
#define ld long double
using namespace std;
using namespace atcoder;
using ll = long long;
using mint = modint998244353;
const ll mod = 998244353;
using Graph = vector<vector<pair<int,int>>>;
//using Graph = vector<vector<int>>;
const vector<int> dx = {1,0,-1,0}, dy = {0,1,0,-1};

int main(){
  // input
  int N,M; cin >> N >> M;
  vector<int> A(N);
  for(int i = 0; i < N; i++) cin >> A[i];
  Graph G(N);
  while(M--){
    int a,b,c;
    cin >> a >> b >> c;
    G[--a].emplace_back(--b,c);
  }
  // prep
  bool inf = 0;
  
  for(int i = 0; i < N; i++){
    // vector<bool> seen(N, false);  // 既に見たことがある頂点か記録する
    priority_queue<pair<ll,int>> pq;
    pq.emplace(0,i);
    vector<ll> satis(N,0);
    satis[i] = 0;
    while(!pq.empty() && !inf){
      auto [tmp,pos] = pq.top();
      pq.pop();
      
      if(satis[pos] > tmp) continue;
      
      for(auto p : G[pos]){
        auto nxt = p.first, cost = p.second;
        if(satis[nxt] < tmp + A[nxt] - cost){
            pq.emplace(tmp+A[nxt]-cost,nxt);
          satis[nxt] = tmp+A[nxt]-cost;
        }
        if(nxt == i){
          if(tmp + A[i] - cost > 0){
            inf = 1; break;
          }
        }
      }
    }
  }
  
  // output
  if(inf) cout << "inf" << endl;
  else{
    priority_queue<pair<ll,int>> pq;
    pq.emplace(A[0],0);
    vector<ll> ans(N,0);
    ans[0] = A[0];
    while(!pq.empty()){
      auto [tmp,pos] = pq.top();
      pq.pop();
      if(ans[pos] > tmp) continue;
      for(auto p : G[pos]){
        auto nxt = p.first, cost = p.second;
        if(ans[nxt] < tmp + A[nxt] - cost){
            pq.emplace(tmp+A[nxt]-cost,nxt);
          ans[nxt] = tmp+A[nxt]-cost;
        }
      }
    }
    cout << ans[N-1] << endl;
  }
}