#include <cstdio>
#include <iostream>
#include <vector>
#include <queue>
#include <utility>
#include <algorithm>
#include <functional>
#include <string>
#include <cstring>
#include <cmath>
#include <map>
#include <set>
#include <bitset>
#include <stack>
#include <iomanip>
#include <fstream>
#define MOD 105011
#define NMAX 1005
#define INF 0x3f3f3f3f
#define pb push_back

using namespace std;

//FILE *fin = freopen("schi.in", "r", stdin);
//FILE *fout = freopen("schi.out", "w", stdout);

typedef pair<int, int> pii;

int memo[NMAX][NMAX];
int days[NMAX];
pii v[NMAX];
int d, n, m;

int solve(int poz, int st) {
	if (memo[poz][st] != -1)
		return memo[poz][st];

	if (days[d] - days[st - 1] == 0)
		return memo[poz][st] = 1;

	int i, res = INF;
	for (i = poz + 1; i < m; ++i) {
		if (v[i].first >= st && days[v[i].first] - days[st] == 0)
			res = min(res, solve(i, v[i].second + 1) + 1);
	}

	return memo[poz][st] =res;
}

int main() {
	int i, x, res;

	cin >> d >> n >> m;

	for (i = 0; i < n; ++i) {
		cin >> x;
		days[x] = 1;
	}

	for (i = 1; i <= d; ++i)
		days[i] += days[i - 1];

	for (i = 0; i < m; ++i)
		cin >> v[i].first >> v[i].second;

	sort(v, v + m);

	res = INF;
	memset(memo, -1, sizeof(memo));
	for (i = 0; i < m; ++i) {
		if (days[v[i].first-1] == 0)
			res = min(res, solve(i, v[i].second + 1));
		else
			break;
	}

	cout << res;

	return 0;
}