#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define ALL(v) v.begin(), v.end()
typedef long long ll;

#include <bits/stdc++.h>
using namespace std;
const ll INF=1LL<<60;

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

using Graph=vector<vector<Edge>>;

template<class T> bool chmin(T& a,T b){
  if(a>b){
    a=b;
    return true;
  }
  else return false;
}

int main(){
  int n,m;
  cin>>n>>m;
  vector<ll> A(n);
  rep(i,n) cin>>A[i];
  Graph G(n),G1(n);
  vector<ll> AA(m),B(m),C(m);
  rep(i,m){
    ll a,b,w;
    cin>>a>>b>>w;
    a--,b--;
    AA[i]=a,B[i]=b,C[i]=w;
    G[a].push_back(Edge(b,w-A[a]));
  }
  
  vector<int> can(n);
  auto dfs=[&](auto dfs,int v,int p)->void{
    can[v]=1;
    for(auto nv:G[v]){
      if(nv.to==p) continue;
      dfs(dfs,nv.to,v);
    }
  };
  dfs(dfs,n-1,-1);
  
  rep(i,m){
    if(can[AA[i]]==0 || can[B[i]==0]) continue;
    G1[AA[i]].push_back(Edge(B[i],C[i]-A[AA[i]]));
  }
  
  bool exist_negative_cycle=false;
  vector<ll> dist(n,INF);
  dist[0]=0;
  rep(i,n){
    bool update=false;
    rep(v,n){
      if(dist[v]==INF) continue;
      for(auto e:G[v]){
        if(chmin(dist[e.to],dist[v]+e.w)){
          update=true;
        }
      }
    }
    if(!update) break;
    if(i==n-1 && update) exist_negative_cycle=true;
  }
  
  if(exist_negative_cycle) cout<<"inf"<<endl;
  else cout<<A[n-1]-dist[n-1]<<endl;
  
  return 0;
}