#include<bits/stdc++.h>
// #include<atcoder/all>
// #include<boost/multiprecision/cpp_int.hpp>

using namespace std;
// using namespace atcoder;
// using bint = boost::multiprecision::cpp_int;
using ll = long long;
using ull = unsigned long long;
using P = pair<int,int>;
using vi = vector<ll>;
using vvi = vector<vi>;
using vvvi = vector<vvi>;
#define rep(i,n) for(ll i = 0;i < (ll)n;i++)
#define ALL(x) (x).begin(),(x).end()
#define sz(c) ((ll)(c).size())
#define LB(A,x) (int)(lower_bound(A.begin(),A.end(),x)-A.begin())
// #define MOD 1000000007
#define MOD 998244353
template<typename T>using min_priority_queue=priority_queue<T,vector<T>,greater<T>>;
template<typename T>ostream&operator<<(ostream&os,vector<T>&v){for(int i = 0;i < v.size();i++)os<<v[i]<<(i+1!=v.size()?" ":"");return os;}
template<typename T>istream&operator>>(istream&is,vector<T>&v){for(T&in:v)is>>in;return is;}
template<typename T1,typename T2>ostream&operator<<(ostream&os,pair<T1,T2>&p){os<<p.first<<" "<<p.second;return os;}
template<typename T1,typename T2>istream&operator>>(istream&is,pair<T1,T2>&p){is>>p.first>>p.second;return is;}



int main(){
  
  ios_base::sync_with_stdio(0), cin.tie(0);
  ll n,m;
  cin >> n >> m;
  vi a(n);cin >> a;
  vvi v(m+n,vi(3));
  rep(i,m){
    cin >> v[i];
    v[i][0]--;v[i][1]--;
    v[i][0] += n;
  }
  rep(i,n){
    v[i+m][0] = i;
    v[i+m][1] = i+n;
    v[i+m][2] = -a[i];
  }
  const ll inf = 1ll << 50;
  vi d(2*n,inf);
  d[0] = 0;
  rep(i,2*n-1)rep(j,n+m){
    ll fr = v[j][0],to = v[j][1],c = v[j][2];
    // if(fr == n-1 && to != 2*n-1)continue;
    if(d[to] <= d[fr]+c)continue;
    d[to] = d[fr] + c;
  }
  ll D = d[2*n-1];
  rep(i,2*n-1)rep(j,n+m){
    ll fr = v[j][0],to = v[j][1],c = v[j][2];
    // if(fr == n-1 && to != 2*n-1)continue;
    if(d[to] <= d[fr]+c)continue;
    d[to] = d[fr] + c;
  }
  if(d[2*n-1] < D){
    cout << "inf\n";
  }else cout << -d[2*n-1] << "\n";
  

  return 0;
}