#include <cstdio>
#include <vector>
#include <unordered_map>
#include <unordered_set>
#include <queue>
#include <algorithm>
using namespace std;
struct node {
    int d, u, hp;
    node(int d = 0, int u = 0, int hp = 0) : d(d), u(u), hp(hp) {}
};
bool operator < (node a, node b) {
    return a.d > b.d;
}
vector<pair<int, int> > G[30010];
unordered_map<int, int> dis[30010];
queue<node> pq;
int n, m, k, x, y, z, a[30010], ans = 1e9;
void dijkstra() {
    pq.emplace(0, 1, k);
    dis[1][k] = 0;
    while (!pq.empty()) {
        node t = pq.front();
        pq.pop();
        // printf("%d %d %d\n", t.u, t.d, t.hp);
        int nowdis = dis[t.u][t.hp];
        if (t.u == n) {
            ans = min(ans, t.d);
        }
        t.hp = min(k, t.hp + a[t.u]);
        for (int i = 0; i < G[t.u].size(); i++) {
            int v = G[t.u][i].first;
            int w = G[t.u][i].second;
            if (t.hp >= w) {
                if (!dis[v].count(t.hp - w)) {
                    dis[v][t.hp - w] = nowdis + 1;
                    pq.emplace(nowdis + 1, v, t.hp - w);
                }
            }
        }
    }
}
int main() {
    scanf("%d%d%d", &n, &m, &k);
    for (int i = 1; i <= n; i++) {
        scanf("%d", &a[i]);
    }
    for (int i = 1; i <= m; i++) {
        scanf("%d%d%d", &x, &y, &z);
        G[x].push_back({y, z});
        G[y].push_back({x, z});
    }
    dijkstra();
    if (ans == 1e9) ans = -1;
    printf("%d\n", ans);
    return 0;
}