#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

int main()
{
    cin.tie(0);
    int M = 0, N = 0;
    cin >> M >> N;
    vector<int> vec(M + N);
    for (int i = 0; i < M + N; i++)
    {
        cin >> vec[i];
    }
    if (N <= M)
    {
        cout << "0" << endl;
        return 0;
    }
    sort(vec.begin(), vec.begin() + M);
    sort(vec.begin() + M, vec.end());
    long long count = 0, temp = M, sum = 0;
    for (int i = 0; i < M; i++)
    {
        for (int j = temp; j < M + N; j++)
        {
            if (vec[j] > vec[i])
            {
                temp = j + 1;
                sum++;
                break;
            }
            else
            {
                count += vec[j];
            }
        }
    }
    if (sum == M)
    {
        cout << count << endl;
    }
    else
    {
        cout << "0" << endl;
    }
    return 0;
}