#include <stdio.h>
#include <algorithm>

using namespace std;

int main()
{
    freopen ("toys.in", "r", stdin);
    freopen ("toys.out", "w" , stdout);
    int n, m, c[5000], p[5000];
    scanf("%d %d", &n, &m);
    for (int i = 0; i < n; i++) scanf("%d", &c[i]);
    for (int i = 0; i < m; i++) scanf("%d", &p[i]);
    sort(c, c + n);
    sort(p, p + m);
    unsigned long long answer = 0;
    for (int i = 0; i < n; i++)
        answer += (p[m - i - 1] * c[n - i - 1]);
    printf("%llu\n", answer);
    fclose(stdin);
    fclose(stdout);
    return 0;
}