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

const int iinf = 1e9;
const ll inf = 1e18;

template<typename T>
ostream& operator<<(ostream &o, vector<T> v) {
    for (int i = 0; i < v.size(); i++)
        o << v[i] << (i+1<v.size()?" ":"");
    return o;
}

struct Edge { int to; ll cost; };

int main() {
    cin.tie(0)->sync_with_stdio(false);

    int N, M, K;
    cin >> N >> M >> K;
    vector<vector<Edge>> G(N+1);
    vector<ll> C(M);
    vector<int> U(M), V(M);
    for(int i = 0; i < M; i++){
        cin >> C[i];
    }
    for(int i = 0; i < M; i++){
        cin >> U[i] >> V[i];
        G[U[i]].push_back({V[i], C[i]});
        G[V[i]].push_back({U[i], C[i]});
    }

    vector<vector<ll>> dist(N+1, vector<ll>(K+1, inf));
    using T = tuple<ll,int,int>;
    priority_queue<T, vector<T>, greater<T>> pq;

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

    while(!pq.empty()){
        auto [d, v, k] = pq.top(); pq.pop();
        if(d > dist[v][k]) continue;
        for(auto &e : G[v]){
            int u = e.to;
            ll c = e.cost;
            if(dist[u][k] > d + c){
                dist[u][k] = d + c;
                pq.emplace(dist[u][k], u, k);
            }
            if(k < K && dist[u][k+1] > d){
                dist[u][k+1] = d;
                pq.emplace(d, u, k+1);
            }
        }
    }

    ll ans = inf;
    for(int k = 0; k <= K; k++){
        ans = min(ans, dist[N][k]);
    }
    cout << (ans==inf?-1:ans) << "\n";
    return 0;
}