#include <vector>
#include <list>
#include <map>
#include <set>
#include <deque>
#include <stack>
#include <bitset>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <ctime>
#include <queue>
#include <cstring>

using namespace std;

#define pb push_back
#define len length()
#define clr clear()

#define eps 0.0000001
#define PI  3.14159265359
#define inf 1999888777

int c[333555],p[333555];

int main() {

    FILE *ff = fopen("toys.in", "r");
    FILE *gg = fopen("toys.out", "w");

    int n,m;

    fscanf(ff,"%d%d", &n, &m);
    for(int i=0; i<n; i++) fscanf(ff,"%d", &c[i]);
    for(int i=0; i<m; i++) fscanf(ff,"%d", &p[i]);

    sort(c,c+n,greater<int>());
    sort(p,p+m,greater<int>());

    int res = 0;
    for(int i=0; i<n; i++) res += c[i]*p[i];

    fprintf(gg,"%d\n", res);

    return 0;
}