#include <bits/stdc++.h>
using namespace std;
int t, n, m;
int a[20];
int b[20];
int dp[200000];
int maxm = 0, maxl = 0;
void f(int i, int l, int my) {
    if (i <= 0) {
        if (l <= t) {
            if (my > maxm) {
                maxm = my;
                maxl = l;
            }
        }
        return;
    }
    f(i - 1, l + a[i - 1], my + b[i - 1]);
    f(i - 1, l, my);
    return;
}
int main() {
    cin >> t >> n;
    for (int i = 0; i < n; i++) {
        cin >> a[i] >> b[i];
    }
    f(n, 0, 0);
    t -= maxl;
    cin >> m;
    for (int i = 0; i < m; i++) {
        int x, y;
        cin >> x >> y;
        for (int j = x; j <= t; j++) {
            dp[j] = max(dp[j], dp[j - x] + y);
        }
    }
    cout << dp[t];
    return 0;
}