#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i, s, t) for (ll i = s; i < (ll)(t); i++)
#define all(x) begin(x), end(x)

template <typename T> bool chmin(T& x, T y) {
	return x > y ? (x = y, true) : false;
}
template <typename T> bool chmax(T& x, T y) {
	return x < y ? (x = y, true) : false;
}

struct IOST {
	IOST() {
		ios::sync_with_stdio(false);
		cin.tie(nullptr);
		cout << fixed << setprecision(20);
	}
} IOST;

void solve() {
	int n, m, k;
	cin >> n >> m >> k;
	vector<int> c(m);
	rep(i, 0, m) cin >> c[i];
	vector<vector<array<int, 2>>> g(n);
	rep(i, 0, m) {
		int u, v;
		cin >> u >> v;
		u--;
		v--;
		g[u].push_back({v, c[i]});
		g[v].push_back({u, c[i]});
	}
	priority_queue<array<ll, 3>, vector<array<ll, 3>>, greater<array<ll, 3>>>
		pq;
	pq.push({0, 0, 0});
	vector stl(k + 1, vector<ll>(n, 0));
	ll ans = 1e18;
	while (!pq.empty()) {
		auto [cs, nk, nw] = pq.top();
		pq.pop();
		if (stl[nk][nw]) continue;
		stl[nk][nw] = 1;
		if (nw == n - 1) {
			chmin(ans, cs);
		}
		for (auto [nx, ad] : g[nw]) {
			if (nk < k && !stl[nk + 1][nx]) {
				pq.push({cs, nk + 1, nx});
			}
			if (!stl[nk][nx]) {
				pq.push({cs + ad, nk, nx});
			}
		}
	}
	if (ans == 1e18) ans = -1;
	cout << ans << "\n";
}

int main() {
	int t = 1;
	// cin >> t;
	rep(i, 0, t) solve();
}