#include <iostream>
#include <stdio.h>
#include <algorithm>
using namespace std;
typedef long long Int;

int n,m;
int c[10001];
int p[10001];

int main()
{
    freopen("toys.in","r",stdin);
    freopen("toys.out","w",stdout);

    int i,j;
    int uk1,uk2;
    Int Cost=0;

    scanf("%d %d",&n,&m);

    for (i=1;i<=n;i++)
    {
        scanf("%d",&c[i]);
    }

    for (i=1;i<=m;i++)
    {
        scanf("%d",&p[i]);
    }

    sort(c+1,c+1+n);
    sort(p+1,p+1+m);

    for (i=n;i>=1;i--)
    {
        Cost=Cost+(Int)c[i]*(Int)p[m-(n-i)];
    }

    printf("%lld\n",Cost);

    return 0;
}