#include<bits/stdc++.h>
#define rep(i,a,b) for(int i=a;i<b;i++)
#define rrep(i,a,b) for(int i=a;i>=b;i--)
#define fore(i,a) for(auto &i:a)
#define all(x) (x).begin(),(x).end()
//#pragma GCC optimize ("-O3")
using namespace std; void _main(); int main() { cin.tie(0); ios::sync_with_stdio(false); _main(); }
typedef long long ll; const int inf = INT_MAX / 2; const ll infl = 1LL << 60;
template<class T>bool chmax(T& a, const T& b) { if (a < b) { a = b; return 1; } return 0; }
template<class T>bool chmin(T& a, const T& b) { if (b < a) { a = b; return 1; } return 0; }
//---------------------------------------------------------------------------------------------------
template<typename T> using min_priority_queue = priority_queue<T, vector<T>, greater<T>>;
/*---------------------------------------------------------------------------------------------------
　　　　　　　　　　　 ∧＿∧
　　　　　 ∧＿∧ 　（´<_｀ ）　 Welcome to My Coding Space!
　　　　 （ ´_ゝ`）　/　 ⌒i     @hamayanhamayan
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　 　　　＼/＿＿＿＿/　（u　⊃
---------------------------------------------------------------------------------------------------*/



int N, M, K;
ll C[101010];
vector<pair<int,ll>> E[101010];

int vis[101010][4];
ll D[101010][4];

void _main() {
    cin >> N >> M >> K;
    rep(i, 0, M) cin >> C[i];
    rep(i, 0, M) {
        int a, b;
        cin >> a >> b;
        a--; b--;
        E[a].push_back({ b, C[i] });
        E[b].push_back({ a, C[i] });
    }

    rep(town, 0, N) rep(coupon, 0, K + 1) D[town][coupon] = infl;
    rep(town, 0, N) rep(coupon, 0, K + 1) vis[town][coupon] = 0;
 
    min_priority_queue<pair<ll, pair<int,int>>> que;
 
    D[0][K] = 0;
    que.push({ 0, {0, K} });
 
    while (!que.empty()) {
        auto q = que.top(); que.pop();
 
        ll cst = q.first;
        int town = q.second.first;
        int coupon = q.second.second;
 
        if (vis[town][coupon]) continue;
        vis[town][coupon] = 1;
 
        fore(p, E[town]) {
            ll cst2 = cst + p.second;
            int town2 = p.first;

            // use coupon
            if (coupon > 0) {
                if (chmin(D[town2][coupon - 1], cst)) que.push({ D[town2][coupon - 1], { town2, coupon - 1 } });
            }

            // not use coupon
            if (chmin(D[town2][coupon], cst2)) que.push({ D[town2][coupon], { town2, coupon } });
        }
    }

    ll ans = infl;
    rep(coupon, 0, K + 1) chmin(ans, D[N - 1][coupon]);
    if (ans == infl) ans = -1;
    cout << ans << endl;
}