#include<bits/stdc++.h>
using namespace std;
using uint = unsigned int;
using ll = long long;
using ull = unsigned long long;
template<class T> using V = vector<T>;
template<class T> using VV = V<V<T>>;
template<class T> using VVV = V<VV<T>>;
template<class T> using VVVV = VV<VV<T>>;
#define rep(i,n) for(ll i=0ll;i<n;i++)
#define REP(i,a,n) for(ll i=a;i<n;i++)
const long long INF = (1LL << 60);
const long long mod99 = 998244353;
const long long mod107 = 1000000007;
const long long mod = mod99;
#define eb emplace_back
#define pb eb
#define be(v) (v).begin(),(v).end()
#define all(i,v) for(auto& i : v)
#define all2(i,j,v) for(auto& [i,j] : v)
template<class T, class U> void chmin(T& t, const U& u) { if (t > u) t = u; }
template<class T, class U> void chmax(T& t, const U& u) { if (t < u) t = u; }

// cin.tie(nullptr);
// ios::sync_with_stdio(false);
// cout << fixed << setprecision(20);

void solve(){
  ll n,m;
  cin >> n >> m;
  V<ll> a(n);
  rep(i,n) cin >> a[i];
  VV<pair<ll,ll>> g(n);
  V<ll> x, y, d;
  rep(i,m){
    ll a,b,c;
    cin >> a >> b >> c;
    a--;
    b--;
    x.eb(a);
    y.eb(b);
    d.eb(c);
    g[b].eb(a, c);
  }
  
  V<ll> ok(n, 0);
  ok[n-1] = 1;
  queue<ll> que;
  que.push(n-1);
  while(!que.empty()){
    ll nd = que.front();
    que.pop();
    for(auto[nx, _]:g[nd]) if(!ok[nx]){
      ok[nx] = 1;
      que.push(nx);
    }
  }
  
  V<ll> dist(n, -INF);
  dist[0] = a[0];
  rep(j, n) rep(i, m) chmax(dist[y[i]], dist[x[i]]-d[i]+a[y[i]]);
  
  ll ans = dist[n-1];
  rep(i, m) if(dist[y[i]] < dist[x[i]]-d[i]+a[y[i]] && ok[y[i]]){
    ans = INF;
  }
  if(ans == INF) cout << "inf" << endl;
  else cout << ans << endl;
}





int main(){
  cin.tie(nullptr);
  ios::sync_with_stdio(false);
  int t=1;
  // cin >> t;
  rep(i,t) solve();
}