#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const ll INF = 1e18;

int main() {
    int N, M, K;
    cin >> N >> M >> K;
    vector<ll> C(M);
    for (int i = 0; i < M; ++i) {
        cin >> C[i];
    }
    vector<vector<pair<int, ll>>> adj(N + 1);
    for (int i = 0; i < M; ++i) {
        int u, v;
        cin >> u >> v;
        adj[u].emplace_back(v, C[i]);
        adj[v].emplace_back(u, C[i]);
    }

    vector<vector<ll>> dist(N + 1, vector<ll>(K + 1, INF));
    priority_queue<pair<ll, pair<int, int>>, vector<pair<ll, pair<int, int>>>, greater<>> pq;

    dist[1][K] = 0;
    pq.emplace(0, make_pair(1, K));

    while (!pq.empty()) {
        auto [current_cost, state] = pq.top();
        auto [u, k] = state;
        pq.pop();

        if (current_cost > dist[u][k]) continue;

        for (auto [v, c] : adj[u]) {
            if (dist[v][k] > current_cost + c) {
                dist[v][k] = current_cost + c;
                pq.emplace(dist[v][k], make_pair(v, k));
            }
            if (k > 0 && dist[v][k-1] > current_cost) {
                dist[v][k-1] = current_cost;
                pq.emplace(dist[v][k-1], make_pair(v, k-1));
            }
        }
    }

    ll ans = INF;
    for (int k = 0; k <= K; ++k) {
        ans = min(ans, dist[N][k]);
    }

    if (ans == INF) {
        cout << -1 << endl;
    } else {
        cout << ans << endl;
    }

    return 0;
}