// s = 1 のもとで O(Q + (N + M) log N)

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

#ifdef LOCAL
#include <debug.hpp>
#else
#define debug(...)
#endif

int main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(20);
    int N, M, Q;
    cin >> N >> M >> Q;
    vector<int> A(N), W;
    for (int i = 0; i < N; i++) cin >> A[i], A[i]--;
    vector<vector<pair<int, int>>> G(N);
    for (int i = 0; i < M; i++) {
        int u, v, w;
        cin >> u >> v >> w, u--, v--;
        W.emplace_back(w);
        G[u].emplace_back(v, w);
        G[v].emplace_back(u, w);
    }

    ranges::sort(W);
    W.erase(ranges::unique(W).begin(), W.end());

    constexpr int INF = (1 << 30) - 1;
    // dist[i] := 店 i に行くまでに必要な巡礼度
    vector<int> dist(N, INF);
    priority_queue<pair<int, int>, vector<pair<int, int>>, greater<>> que;
    dist[0] = 0;
    que.emplace(dist[0], 0);
    while (!que.empty()) {
        auto [expected, v] = que.top();
        que.pop();
        if (dist[v] < expected) continue;
        for (auto [u, w] : G[v]) {
            int c = max(dist[v], w);
            if (dist[u] > c) {
                dist[u] = c;
                que.emplace(dist[u], u);
            }
        }
    }

    // ans[i] := 系列 i を取るための最小の巡礼度
    vector<int> ans(N, INF);
    for (int i = 0; i < N; i++) ans[A[i]] = min(ans[A[i]], dist[i]);
    ranges::sort(ans);

    auto solve = [&](int s, int c) -> int { return (ans[c - 1] == INF ? -1 : ans[c - 1]); };

    while (Q--) {
        int s, c;
        cin >> s >> c, s--;
        assert(s == 0);
        cout << solve(s, c) << "\n";
    }
}