#include<iostream>
using namespace std;

const int MAXN=1005;
int n,x;
int a[MAXN],b[MAXN];
long long ans=0;

inline int read(){
  	int x=0,w=1;
  	char ch=0;
  	while(ch<'0' || ch>'9'){ 
    	if(ch=='-') w=-1;
    	ch=getchar();
  	}
  	while(ch>='0' && ch<='9'){
    	x=x*10+(ch-'0');
    	ch=getchar();
  	}
  	return x*w;
}
int main(){
	freopen("running.in","r",stdin);
	freopen("running.out","w",stdout);
	n=read(),x=read();
	
	for(int i=1;i<=n;i++) a[i]=read();
	for(int i=1;i<=n;i++){
		b[i]=read();
		ans+=((a[i]-b[i])*x);
		if(ans>10000){
			cout<<"2 hard 4 me\n";
			return 0;
		}
	}
	cout<<ans;
	return 0;
}