#include <iostream>
#include <cstdio>
#include <cmath>
#include <vector>
#include <cstring>
#include <algorithm>
using namespace std;
const int N = 505;
const int M = 1e4 + 5;
const int inf = 0x3f3f3f3f;

int n, m;
int p[M] = {0};
int c[N] = {0}, e[N] = {0};
int f[M * 2] = {0};

int main() {
	scanf("%d%d", &m, &n);
	for (int i = 1; i <= m; i++)
		scanf("%d", &p[i]);
	sort(p + 1, p + m + 1, [](int x, int y){return x > y;});
	memset(f, 0x3f, sizeof f);
	f[0] = 0;
	for (int i = 1; i <= n; i++) {
		scanf("%d%d", &c[i], &e[i]);
		for (int j = m * 2; j >= c[i]; j--)
			f[j] = min(f[j], f[j - c[i]] + e[i]);
	}
	for (int j = m * 2; j >= 0; j--)
		f[j] = min(f[j], f[j + 1]);
	int ans = 0, sum = 0;
	for (int j = 1; j <= m; j++) {
		sum += p[j];
		ans = max(ans, sum - f[j]);
	}
	cout << ans << endl;
	return 0;
}