#include <bits/stdc++.h>

using namespace std;

#define FOR(i, a, b) for(int i = (a); i < (b); i++)
#define RFOR(i, a, b) for(int i = (a) - 1; i >= (b); i--)
#define SZ(a) int(a.size())
#define ALL(a) a.begin(), a.end()
#define PB push_back
#define MP make_pair
#define F first
#define S second

typedef long long LL;
typedef vector<int> VI;
typedef pair<int, int> PII;
typedef double db;

const int INF = 1'000'000'447;
const int N = 100'447;
const int W = 104;
VI g[N];
VI a[N];
int w[N];
int d[W][N];
int que[N];
int qh = 0, qt = 0;

int main()
{
	ios::sync_with_stdio(0);
	cin.tie(0);
	
	int n, m, q;
	cin >> n >> m >> q;
	FOR (i, 0, n)
	{
		cin >> w[i];
		w[i]--;
		a[w[i]].PB(i);
	}
	FOR (i, 0, W) FOR (j, 0, n) d[i][j] = INF;
	FOR (i, 0, m)
	{
		int u, v;
		cin >> u >> v;
		u--, v--;
		g[u].PB(v);
		g[v].PB(u);
	}
	FOR (c, 0, 100)
	{
		qh = 0, qt = 0;
		for (auto v : a[c])
		{
			que[qh++] = v;
			d[c][v] = 0;
		}
		while (qh != qt)
		{
			int v = que[qt++];
			for (auto u : g[v])
			{
				if (d[c][u] > d[c][v] + 1)
				{
					d[c][u] = d[c][v] + 1;
					que[qh++] = u;
				}
			}
		}
	}
	FOR (i, 0, n)
	{
		FOR (c, 1, W)
		{
			d[c][i] = min(d[c][i], d[c - 1][i]);
		}
	}
	FOR (i, 0, q)
	{
		int v, s;
		cin >> v >> s;
		v--, s--;
		if (d[s][v] == INF)
			d[s][v] = -1;
		cout << d[s][v] << '\n';
	}
	
	return 0;
}