#include <bits/stdc++.h>
using namespace std;

int main() {
  int N, M;
  cin >> N >> M;
  vector<long long> A(N);
  for(int i = 0; i < N; i++) {
    cin >> A[i];
  }
  vector<int> a(M), b(M);
  vector<long long> c(M);
  for(int i = 0; i < M; i++) {
    cin >> a[i] >> b[i] >> c[i];
    a[i]--, b[i]--;
  }
  const long long INF = 1LL<<55;
  vector<long long> dp(N, INF);
  dp[0] = 0;
  for(int i = 0; i < N; i++) {
    for(int j = 0; j < M; j++) {
      if(dp[b[j]] > dp[a[j]]-(A[a[j]]-c[j])) {
        dp[b[j]] = dp[a[j]]-(A[a[j]]-c[j]);
      }
    }
  }
  for(int j = 0; j < M; j++) {
    if(dp[b[j]] > dp[a[j]]-(A[a[j]]-c[j])) {
      cout << "inf" << endl;
      return 0;
    }
  }
  cout << A[N-1]-dp[N-1] << endl;
}