#include <bits/stdc++.h>
// #include<atcoder/all>
// using namespace atcoder;
#define rep(i,n) for(int i=0;i<n;i++)
#define FOR(i,start,end) for(int i=start;i<=end;i++)
const int INF = 1001001001;
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define Sort(a) sort(a.begin(), a.end())
#define Rort(a) sort(a.rbegin(), a.rend())
typedef long long ll;
const ll MOD=1000000007;
using namespace std;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
template<class T>auto MAX(const T& a) { return *max_element(a.begin(),a.end()); }
template<class T>auto MIN(const T& a) { return *min_element(a.begin(),a.end()); }
template<class T, class U>U SUM(const T& a, const U& v) { return accumulate(a.begin(),a.end(), v); }
template<class T, class U>U COUNT(const T& a, const U& v) { return count(a.begin(),a.end(), v); }
template<class T, class U>int LOWER(const T& a, const U& v) { return lower_bound(a.begin(),a.end(), v) - a.begin(); }
template<class T, class U>int UPPER(const T& a, const U& v) { return upper_bound(a.begin(),a.end(), v) - a.begin(); }
int GCD(int a, int b) { return b ? GCD(b, a%b) : a; }
int LCM(int a, int b) { int g = GCD(a, b); return a / g * b; }
typedef long double ld;
typedef unsigned long long int ull;
typedef pair<int,int> P;
typedef vector<int> vi;
typedef vector<char> vc;
typedef vector<bool> vb;
typedef vector<double> vd;
typedef vector<string> vs;
typedef vector<ll> vll;
typedef vector<pair<int, int>> vpii;
typedef vector<pair<ll, ll>> vpll;
typedef vector<vi> vvi;
typedef vector<vvi> vvvi;
typedef vector<vc> vvc;
typedef vector<vs> vvs;
typedef vector<vll> vvll;
typedef map<int, int> mii;
typedef set<int> si;
//---------------------------------------------------------------------------------------------------

int main(void){
    // Your code here!
    // Your code here!
    int n,m; cin >> n >> m;
    vi a(m),b(m),c(m);
    rep(i,m) {
        cin >> a[i] >> b[i] >> c[i];
        a[i]--;
        b[i]--;
    }
    vi t(n);
    rep(i,n) cin >> t[i];
    vector<vector<P>> Graph(n);
    rep(i,m) {
        Graph[a[i]].push_back({b[i],c[i]});
        Graph[b[i]].push_back({a[i],c[i]});
    }
    priority_queue<P,vector<P>, greater<P>> que;
    vi d(n,INF);
    d[0] = 0;
    que.push({0,0}); // first はcost、second はnode
    while(!que.empty()) {
        P p = que.top(); que.pop();
        int v = p.second;
        if (d[v] < p.first) continue;
        rep(i,Graph[v].size()) {
            P e = Graph[v][i];
            if (d[e.first] > d[v] + t[v] + e.second/(p.first+t[v])) {
                d[e.first] = d[v] + t[v] + e.second/(p.first+t[v]);
                que.push({e.first,d[e.first]});
            }
        }
    }
    cout << d[n-1] << endl;
}