//g++ 2.cpp -std=c++14 -I .
#include <bits/stdc++.h>
using namespace std;

#include <atcoder/all>
using namespace atcoder;

using ll = long long;
using ld = long double;

using vi = vector<int>;
using vvi = vector<vi>;
using vll = vector<ll>;
using vvll = vector<vll>;
using vld = vector<ld>;
using vvld = vector<vld>;

#define fi first
#define se second
#define pb push_back
#define all(a) a.begin(),a.end()
#define rep(i,start,end) for(ll i=start;i<(ll)(end);i++)
#define per(i,start,end) for(ll i=start;i>=(ll)(end);i--)

vvi dp(110,vi(12000,1e9));
using T = tuple<int,int,int>;

int main(){
  ios::sync_with_stdio(false);
  cin.tie(nullptr);

  int n,m;
  cin>>n>>m;

  vector<vector<pair<int,int>>> g(n);
  rep(i,0,m){
    int a,b,c;
    cin>>a>>b>>c;
    a--;b--;
    g[a].pb({b,c});
    g[b].pb({a,c});
  }

  vi t(n);
  rep(i,0,n){
    cin>>t[i];
  }

  dp[0][0]=0;

  priority_queue<T,vector<T>,greater<T>> que;
  que.push({0,0,0});

  while(!que.empty()){
    auto[now,now2,time]=que.top();
    que.pop();

    if(time>dp[now][now2]||time>11000)continue;

    for(auto[next,len]:g[now]){
      if(dp[next][now2+t[now]]>time+t[now]+len/(now2+t[now])){
        dp[next][now2+t[now]]=time+t[now]+len/(now2+t[now]);
        que.push({next,now2+t[now],dp[next][now2+t[now]]});
      }
    }
  }

  int ans=1e9;
  rep(i,0,11000){
    ans=min(ans,dp[n-1][i]);
  }

  cout<<ans<<endl;
}