#include <bits/stdc++.h>
using namespace std;
#include <atcoder/all>
using namespace atcoder;
using ll = long long;
using VI = vector<int>;
using VVI = vector<VI>;
using VL = vector<ll>;
using VVL = vector<VL>;
using VD = vector<double>;
using VVD = vector<VD>;
using VS = vector<string>;
using P = pair<ll,ll>;
using VP = vector<P>;
#define rep(i, n) for (ll i = 0; i < ll(n); i++)
#define out(x) cout << x << endl
#define dout(x) cout << fixed << setprecision(10) << x << endl
#define all(a) (a).begin(),(a).end()
#define rall(a) (a).rbegin(),(a).rend()
#define sz(x) (int)(x.size())
#define re0 return 0
#define pcnt __builtin_popcountll
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
constexpr int inf = 1e9;
constexpr ll INF = 1e18;
//using mint = modint1000000007;
using mint = modint998244353;
int di[4] = {1,0,-1,0};
int dj[4] = {0,1,0,-1};

struct Edge{
    int to;
    ll w;
    Edge(int to,ll w):to(to),w(w) {}
};

int main(){
    ll n,m;
    cin >> n >> m;
    VL a(n);
    rep(i,n) cin >> a[i];
    vector<vector<Edge>> g(n);
    vector<vector<Edge>> g2(n);
    rep(i,m){
        ll u,v,c;
        cin >> u >> v >> c;
        u--,v--;
        g[u].emplace_back(v,c-a[v]);
        g2[v].emplace_back(u,c-a[v]);
    }
    auto bfs0 = [&](ll s){
        VL res(n);
        res[s] = 1;
        queue<ll> q;
        q.emplace(s);
        while(sz(q)){
            ll v = q.front();
            q.pop();
            for(auto e:g[v]){
                if(res[e.to]) continue;
                res[e.to] = 1;
                q.emplace(e.to);
            }
        }
        return res;
    };
    auto bfs1 = [&](ll s){
        VL res(n);
        res[s] = 1;
        queue<ll> q;
        q.emplace(s);
        while(sz(q)){
            ll v = q.front();
            q.pop();
            for(auto e:g2[v]){
                if(res[e.to]) continue;
                res[e.to] = 1;
                q.emplace(e.to);
            }
        }
        return res;
    };
    VL dist0 = bfs0(0);
    VL dist1 = bfs1(n-1);
    set<ll> need;
    rep(i,n){
        if(dist0[i]==0) continue;
        if(dist1[i]==0) continue;
        need.insert(i);
    }
    bool exist_negative_cycle = false;
    vector<ll> dist(n,INF);
    dist[0] = 0;
    for(int iter = 0;iter < n;iter++){
        bool update = false;
        for(int v = 0;v < n;v++){
            if(dist[v] == INF) continue;
        
        for(auto e:g[v]){
            if(!need.count(e.to)) continue;
            if(chmin(dist[e.to],dist[v]+e.w)){
                update = true;
            }
        }
        }
        if(!update) break;
        if(iter == n-1 && update) exist_negative_cycle = true;
    }
    if(exist_negative_cycle) cout << "inf" << endl;
    else {
        ll ans = -dist[n-1];
        ans += a[0];
        out(ans);
    }
}