#include <iostream>
#include <algorithm>
#include <stdio.h>
#include <vector>
#include <cstdio>

using namespace std;

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

    int n,m;
    cin >> n >> m;
    vector<int> iv;
    vector<int> sh;
    for(int i = 0;i < n;i++){
        int t;
        cin >> t;
        iv.push_back(t);
    }
    for(int i = 0;i < m;i++){
        int x;
        cin >> x;
        sh.push_back(x);
    }
    sort(sh.rbegin(),sh.rend());
    sort(iv.rbegin(),iv.rend());
    long long int sum = 0;
    for(int i =0;i < n;i++){
        sum += iv[i] * sh[i];
    }
    cout << sum << endl;
    return 0;
}