#include <algorithm>
#include <cstdio>
 
using namespace std;
 
#define maxn 5000
#define maxm 100000
 
int main(){
 
    int i,j,n,m,p,cost[maxm+1],a[maxn];
    long long int dp[maxn],opt,c;
 
    scanf("%d%d",&n,&m);
    for(i=0;i<n;i++)scanf("%d",&a[i]);
    sort(a,a+n);
 
    for(i=1;i<=m;i++)scanf("%d",&cost[i]);
    for(i=m-1;i>0;i--)
        if(cost[i]>cost[i+1])cost[i]=cost[i+1];
 
    for(i=0;i<n;i++){
        p=a[i]+1;
	    opt=cost[p-a[0]];
	    for(j=0;j<i;j++){
	       c=dp[j]+cost[p-a[j+1]];
	       if(c<opt)opt=c;
	    }
	    dp[i]=opt;
    }
 
    printf("%lld\n",dp[n-1]);
    return 0;
}
 

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