#include<bits/stdc++.h>
#define int long long
using namespace std;
auto read = [](){
	int x;
	scanf("%lld", &x);
	return x;
};
int ans = 0;
signed main(){
	freopen("running.in", "r", stdin);
	freopen("running.out", "w", stdout);
	int n = read(), x = read(), a[1005], b[1005];
	for(int i = 1; i <= n; i ++)
	a[i] = read();
	for(int i = 1; i <= n; i ++)
	b[i] = read();
	for(int i = 1; i <= n; i ++){
		ans += x * (a[i] - b[i]);
		if(ans > 10000){
			printf("2 hard 4 me");
			return 0;
		}
	}
	printf("%lld", ans);
	return 0;
}