#include <bits/stdc++.h>

[[nodiscard]] static inline constexpr std::vector<std::vector<std::pair<uint_least32_t, uint_least32_t>>> prepare(const uint_fast32_t N, const uint_fast32_t M, const std::vector<uint_least32_t>& C, const std::vector<std::pair<uint_least32_t, uint_least32_t>>& bridges) noexcept
{
	std::vector<std::vector<std::pair<uint_least32_t, uint_least32_t>>> next_of(N + 1);
	for (uint_fast32_t i = 0; i != M; ++i)
		next_of[bridges[i].first].emplace_back(bridges[i].second, C[i]), next_of[bridges[i].second].emplace_back(bridges[i].first, C[i]);

	return next_of;
}

[[nodiscard]] static inline int_fast64_t solve(const uint_fast32_t N, const uint_fast32_t K, const std::vector<std::vector<std::pair<uint_least32_t, uint_least32_t>>>& next_of) noexcept
{
	std::vector<std::array<uint_least64_t, 4>> dist(N + 1, { UINT_LEAST64_MAX, UINT_LEAST64_MAX, UINT_LEAST64_MAX, UINT_LEAST64_MAX });
	std::priority_queue<std::tuple<uint_least64_t, uint_least32_t, uint_least32_t>, std::vector<std::tuple<uint_least64_t, uint_least32_t, uint_least32_t>>, std::greater<std::tuple<uint_least64_t, uint_least32_t, uint_least32_t>>> pq;
	for (uint_fast32_t i = 0; i <= K; ++i) dist[1][i] = 0, pq.emplace(0, i, 1);

	while (!pq.empty())
	{
		const auto [cur_dist, used_ticket, cur_pos] = pq.top();
		pq.pop();
		if (cur_dist != dist[cur_pos][used_ticket]) continue;

		for (const auto& [next_pos, cost] : next_of[cur_pos])
		{
			if (dist[next_pos][used_ticket] > cur_dist + cost)
				dist[next_pos][used_ticket] = cur_dist + cost, pq.emplace(cur_dist + cost, used_ticket, next_pos);
			if (used_ticket < K && dist[next_pos][used_ticket + 1] > cur_dist)
				dist[next_pos][used_ticket + 1] = cur_dist, pq.emplace(cur_dist, used_ticket + 1, next_pos);
		}
	}

	return dist[N][K];
}

int main()
{
	std::cin.tie(nullptr);
	std::ios::sync_with_stdio(false);

	uint_fast32_t N, M, K;
	std::cin >> N >> M >> K;
	std::vector<uint_least32_t> C(M);
	std::vector<std::pair<uint_least32_t, uint_least32_t>> bridges(M);
	for (auto& c : C) std::cin >> c;
	for (auto& [u, v] : bridges) std::cin >> u >> v;

	std::cout << solve(N, K, prepare(N, M, C, bridges)) << '\n';
	return 0;
}