#include <bits/stdc++.h>
#include <atcoder/all>

using namespace std;
using namespace atcoder;

using ll = long long;
using mint = modint998244353;

ll solveF(ll H, ll W, ll K) {
    vector<vector<mint>> dp(W + 1, vector<mint>(1 << H, 0));
    dp[0][(1 << H) - 1] = 1LL;
    for (ll j = 0; j < W; j++) {
        for (ll s = 0; s < (1 << H); s++) {
            for (ll t = 0; t < (1 << H); t++) {
                ll u = s & t;
                ll cnt = __builtin_popcount(u);
                if (cnt >= K) {
                    dp[j + 1][t] += dp[j][s];
                }
            }
        }
    }
    mint ans = 0;
    for (ll s = 0; s < (1 << H); s++) {
        ans += dp[W][s];
    }
    return ans.val();
}

ll solveFNaive(ll H, ll W, ll K) {
    return 0;
}

typedef ll Weight;
struct Edge{
    int from, to;
    Weight weight;
    int rev;     // 無向グラフの対の辺
    Edge(int from, int to, Weight weight) :
            from(from), to(to), weight(weight) { }
    Edge(int from, int to, Weight weight, int rev) :
            from(from), to(to), weight(weight), rev(rev){ }
};
bool operator < (const Edge &a, const Edge &b){
    if(a.weight != b.weight) return a.weight > b.weight; if(a.from != b.from) return a.from > b.from;
    return  a.to > b.to;
}
typedef vector<Edge> Edges;
typedef vector<Edges> Graph;
typedef vector<Weight> Array;
typedef vector<Array> Matrix;

void addFlowEdge(Graph &g, int a, int b, Weight c){
    g[a].push_back(Edge(a, b, c, g[b].size()));
    g[b].push_back(Edge(b, a, 0, g[a].size() - 1));
}
void addUndirectedEdge(Graph &g, int a, int b, Weight c){
    g[a].push_back(Edge(a, b, c, g[b].size()));
    g[b].push_back(Edge(b, a, c, g[a].size() - 1));
}

const Weight INF = 1e17;

bool bellmanFord(const Graph &g, int s, vector<Weight> &dist, vector<int> &prev){
    int n = g.size();
    bool nagativeRoop = false;
    dist.assign(n, INF); dist[s] = 0;
    prev.assign(n, -1);
    for(int k = 0; k < 4 * n; ++k){
        for(int v = 0; v < n; ++v){
            for(Edges::const_iterator i=g[v].begin(); i != g[v].end(); ++i){
                if(dist[i -> from] != INF && dist[i -> to] > dist[i -> from] + i -> weight){
                    dist[i -> to] = dist[i -> from] + i-> weight;
                    prev[i -> to] = i -> from;
                    if(k == 4 * n - 1 && i -> to == n - 1){
                        dist[i -> to] = -INF;
                        nagativeRoop = true;
                    }
                }
            }
        }
    }
    return nagativeRoop;
}

int main() {
    ll N, M;
    cin >> N >> M;
    vector<ll> A(N);
    for (ll i = 0; i < N; i++) {
        cin >> A[i];
    }

    Graph g(N);
    for (ll i = 0; i < M; i++) {
        ll a, b, c;
        cin >> a >> b >> c;
        a--; b--;
        g[a].push_back(Edge(a, b, c - A[b]));
    }

    vector<Weight> dist;
    vector<int> prev;
    bool negativeRoop = bellmanFord(g, 0, dist, prev);

    if (negativeRoop) {
        cout << "inf" << endl;
    } else {
        cout << A[0] - dist[N - 1] << endl;
    }

    return 0;
}