#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
#define rep(i, n) for(int i=0;i<(n);++i)
#define rep1(i, n) for(int i=1;i<=(n);i++)
#define ll long long
using mint = modint998244353;
using P = pair<ll,ll>;
using lb = long double;
using T = tuple<ll, ll, ll>;
#ifdef LOCAL
#  include <debug_print.hpp>
#  define dbg(...) debug_print::multi_print(#__VA_ARGS__, __VA_ARGS__)
#else
#  define dbg(...) (static_cast<void>(0))
#endif

int main()
{
    int n, m;
    cin >> n >> m;
    vector<int> a(n);
    rep(i,n) cin >> a[i];
    vector<vector<pair<int, int>>> g(n), rev(n);
    rep(i,m){
        int a, b, c;
        cin >> a >> b >> c;
        --a;--b;
        g[a].emplace_back(b,c);
        rev[b].emplace_back(a,c);
    }
    vector<int> cnt(n);
    queue<int> q;
    q.push(0);
    while(!q.empty()) {
        int u = q.front();q.pop();
        cnt[u]++;
        for(auto [v, c] : g[u]) {
            if(cnt[v]==0) {
                q.push(v);
            }
        }
    }
    q.push(n-1);
    while(!q.empty()) {
        int u = q.front();q.pop();
        cnt[u]++;
        for(auto [v, c] :rev[u]) {
            if(cnt[v]==1) {
                q.push(v);
            }
        }
    }
    vector<ll> dist(n, -1e18);
    dist[0] = 0;
    dbg(cnt);
    rep(j,2*n+1) {
        bool upd = false;
        rep(i,n-1){
            if(cnt[i]!=2) continue;
            for(auto [v, c] : g[i]) {
                if(cnt[v]!=2) continue;
                if(dist[v]<dist[i] + a[i]-c) {
                    dist[v] = dist[i] + a[i] - c;
                    upd = true;
                }
            }
       }
       if(j==2*n && upd) {
            cout << "inf" << endl;
            return 0;
       }
    }
    cout << dist[n-1] + a[n-1] << endl;
    return 0;
}