#include <bits/stdc++.h>
#include <cassert>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long;
using mint = modint998244353;
//using mint = modint1000000007;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define repu(i, s, t) for (int i = (int)(s); i < (int)(t); i++)
#define repd(i, s, t) for (int i = (int)(s)-1; i >= (int)(t); i--)
#define all(v) v.begin(), v.end()
template<typename T> bool chmax(T &a, const T b) { if(a >= b) return false; a = b; return true; }
template<typename T> bool chmin(T &a, const T b) { if(a <= b) return false; a = b; return true; }
template<typename T> istream& operator>>(istream &in, vector<T> &a) { for(T &x: a) in >> x; return in; }
template<typename T> ostream& operator<<(ostream &out, const vector<T> &a) { for(const T &x: a) out << x << ' '; return out; }
const int di[] = {1, 0, -1, 0, 1, 1, -1, -1, 0};
const int dj[] = {0, 1, 0, -1, -1, 1, 1, -1, 0};


using COST = ll;
const COST Z = 0;
const COST E = 1;
const COST INF = 1e18;
struct DIJ {
    struct EDGE{
        int to; COST cost;
    };
    using EList = vector<EDGE>;
    using GRAPH = vector<EList>;
    using pci = pair<COST, int>;

    int n;
    GRAPH g;
    vector<vector<COST>> dist;
    DIJ(int n_): n(n_), g(n_), dist(n_) {}
    void add_edge(int a, int b, COST c = E) {
        g[a].push_back(EDGE{b, c});
    }
    vector<COST>& operator[](int i) {
        if(!dist[i].size()) solve(i);
        return dist[i];
    }
    void solve(int s) {
        dist[s].resize(n, INF);
        priority_queue<pci, vector<pci>, greater<pci>> wait;
        dist[s][s] = Z;
        wait.emplace(Z, s);
        while(!wait.empty()) {
            int pos; COST cost;
            tie(cost, pos) = wait.top(); wait.pop();
            if(dist[s][pos] < cost) continue;
            for(auto ed : g[pos]) {
                COST tmp = cost + ed.cost;
                if(dist[s][ed.to] <= tmp) continue;
                dist[s][ed.to] = tmp;
                wait.emplace(tmp, ed.to);
            }
        }
    }
};

int main() {
    int n, m;
    cin >> n >> m;
    vector<int> w(n);
    cin >> w;

    DIJ g(n);
    rep(i, m) {
        int u, v; ll t;
        cin >> u >> v >> t;
        u--; v--;
        g.add_edge(u, v, t);
        g.add_edge(v, u, t);
    }

    vector<int> ord(n);
    iota(all(ord), 0);
    sort(all(ord), [&](int l, int r) { return g[0][l] < g[0][r]; });
    map<ll, int> skip;
    skip[0] = 0;
    int pre = 0, ls = 0;
    rep(i, n) {
        if(w[ord[i]] >= w[ord[pre]]) continue;
        int tmp = w[ord[pre]] - w[ord[i]];
        ll bord = (g[0][ord[i]] - g[0][ord[pre]] + tmp - 1) / tmp;
        if(bord >= ls) {
            skip[bord] = i;
            pre = i;
            ls = bord;
        }
    }

    ll ans = g[0][n-1];
    rep(i, n) {
        int p = (*--skip.upper_bound(w[i])).second;
        chmin(ans, g[0][ord[p]] + g[n-1][i] + ll(w[ord[p]]) * w[i]);
    }
    cout << ans << endl;
    return 0;
}