#include <cstdio>
#include <iostream>
#include <cstring>
#include <string>
#include <vector>
#include <queue>
#include <algorithm>
using namespace std;

typedef pair <int, int> ii;

const int Maxn = 1005;

int d, n, m;
int days[Maxn];
vector <int> seq[Maxn];
int dp[Maxn];

int Get(int l, int r)
{
	return days[r] - (l? days[l - 1]: 0);
}

int main()
{
	scanf("%d %d %d", &d, &n, &m);
	for (int i = 0; i < n; i++) {
		int cur; scanf("%d", &cur);
		days[cur]++;
	}
	for (int i = 1; i <= d; i++)
		days[i] += days[i - 1];
	for (int i = 0; i < m; i++) {
		int a, b; scanf("%d %d", &a, &b);
		seq[a].push_back(b);
	}
	fill(dp, dp + Maxn, Maxn);
	dp[0] = 0;
	for (int i = 0; i <= d; i++) {
		if (Get(i, i) == 0) dp[i + 1] = min(dp[i + 1], dp[i]);
		for (int j = 0; j < seq[i].size(); j++) {
			int r = seq[i][j];
			if (Get(i, r) > 0) dp[r + 1] = min(dp[r + 1], dp[i] + 1);
		}
	}
	printf("%d\n", dp[d + 1]);
	return 0;
}