#include<bits/stdc++.h>
using namespace std;
int a[1001], b[1001];
int main() {
	bool flag = false;
	int n, m, k;
	cin >> n >> m >> k;
	for (int i = 1; i <= k; i++) {
		cin >> a[i];
	}
	for (int i = 1; i <= k; i++) {
		cin >> b[i];
	}
	int nown = n, nowm = m;
	int minn = 0xffff;
	for (int i = 1; i <= k; i++) {
		n = nown, m = nowm;
		for (int j = 1; j <= b[i]; j++) {
			n -= j;
			m -= a[i] * j;
			if (minn > n - m && n - m > 0) {
				minn = n - m;
				flag = true;
			}
		}
	}
	if (flag == true || minn == 0) {
		cout << minn;
	} else {
		cout << "No";
	}
	return 0;
}