#include <algorithm>
#include <cassert>
#include <cmath>
#include <cstring>
#include <iostream>
#include <set>
#include <tuple>
#include <utility>
#include <vector>
using namespace std;
using i8 = int8_t;
using i32 = int;
using i64 = long long;
using i128 = __int128;
using u64 = unsigned long long;
using ll = long long;

void _main();
int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  _main();
}

i64 pow(i64 x, i64 n) {
  i64 res = 1;
  while (n > 0) {
    if (n & 1)
      res *= x;
    x *= x;
    n >>= 1;
  }
  return res;
}

i64 pow(i64 x, i64 n, i64 m) {
  i64 res = 1;
  while (n > 0) {
    if (n & 1)
      res = res * x % m;
    x = x * x % m;
    n >>= 1;
  }
  return res;
}

const i64 inf = 1ll << 60;

void _main() {
  i64 n, m;
  cin >> n >> m;
  vector<i64> a(n);
  for (i64 i = 0; i < n; i++) {
    cin >> a[i];
  }
  vector<i64> u(m);
  vector<i64> v(m);
  vector<i64> c(m);
  for (i64 i = 0; i < m; i++) {
    cin >> u[i] >> v[i] >> c[i];
    u[i]--, v[i]--;
    c[i] = a[v[i]] - c[i];
  }
  vector<i64> max(n, -inf);
  max[0] = a[0];
  for (i64 cnt = 0; cnt <= 5 * n; cnt++) {
    for (i64 i = 0; i < m; i++) {
      if (max[v[i]] < max[u[i]] + c[i]) {
        max[v[i]] = max[u[i]] + c[i];
        if (cnt > n && v[i] == n - 1) {
          cout << "inf\n";
          return;
        }
      }
    }
  }
  cout << max[n - 1] << "\n";
}