#include <bits/stdc++.h>
using namespace std;
const int N = 30050;
int n, m, a[N], lim;
struct State{
    int u, val, tim;
};
int Mx[N];
queue<State> q;
vector<pair<int, int>> g[N];
int main(){
    ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
    cin >> n >> m >> lim;
    for(int i = 1;i <= n;i++) cin >> a[i];
    for(int i = 1;i <= m;i++){
        int u, v, w;
        cin >> u >> v >> w;
        g[u].push_back({v, w});
        g[v].push_back({u, w});
    }
    q.push({1, lim, 0});
    while(!q.empty()){
        State cur = q.front();q.pop();
        int u = cur.u, t = cur.tim, val = cur.val;
        if(u == n){
            cout << t << endl;
            return 0;
        }
        for(pair<int, int> nxt : g[u]){
            int v = nxt.first, w = nxt.second;
            if(val <= w) continue;
            int gt = min(lim, val - w + a[v]);
            if(Mx[v] >= gt) continue;
            q.push({v, gt, t + 1});
            Mx[v] = gt;
        }
    }
    cout << -1 << endl;
    return 0;
}