#include<iostream>
#include<vector>
#include<set>
using namespace std;
vector<int> bfs(int n,int m,vector<vector<int>>rotti,int start){
  vector<int>stack{start};
  int iti=0,hako;
  set<int>irane{start};
  while (stack.size()>iti){
    hako=stack[iti];
    for (int i=0;i<rotti[hako-1].size();i++){
      if (irane.count(rotti[hako-1][i])>0)continue;
      irane.insert(rotti[hako-1][i]);
      stack.emplace_back(rotti[hako-1][i]);
    }
    iti++;
  }
  vector<int>ans(n,0);
  //連結してるなら１
  for (int i=0;i<n;i++)if(irane.count(i+1)>0)ans[i]=1;
  return ans;
}
vector<long long> dijkstra_negative(int n,int m,vector<vector<vector<int>>>graph,int start,vector<int>num){
  //連結じゃない頂点には手をださない
  //vector<int>numの中身はそれぞれの頂点がスタート地点から連結かどうか（連結なら１）
  vector<long long>amount(n,1e12);
  int check;
  amount[start-1]=0;
  for (int q=0;q<n+1;q++){
    check=0;
    for (int i=0;i<n;i++){
      if(num[i]==0)continue;
      for (int ipp=0;ipp<graph[i].size();ipp++){
        if(amount[graph[i][ipp][0]-1]<=amount[i]+graph[i][ipp][1])continue;
        check=1;
        amount[graph[i][ipp][0]-1]=amount[i]+graph[i][ipp][1];
      }
    }
    if(check==0)break;
  }
  //負の経路が存在する
  if(check==1){
    amount[start-1]=-1;
    return amount;
  }
  return amount;
}
int main()
{
  int n,m;
  cin >> n >> m;
  vector<int>A(n);
  vector<vector<vector<int>>>graph(n);
  vector<vector<int>>graph2(n);
  for(int i=0;i<n;i++)cin >> A[i];
  for(int i=0;i<m;i++){
    int a,b,c;
    cin >> a >> b >> c;
    graph[a-1].push_back({b,c-A[b-1]});
    graph2[a-1].emplace_back(b);
  }
  vector<int>num=bfs(n,m,graph2,1);
  vector<long long>amount=dijkstra_negative(n,m,graph,1,num);
  if(amount[0]==-1)cout << "inf" << endl;
  else cout << amount[n-1]*-1+A[0] << endl;
}