#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>

using namespace std;

int m,n;
int attack[100010];
int defend[100010];
bool v[100010];
int ans;

int main() {
    cin >> m >> n;
    for(int i = 1;i <= m;i++) {
        cin >> defend[i];
    }
    for(int i = 1;i <= n;i++) {
        cin >> attack[i];
    }
    sort(defend+1,defend+1+m);
    sort(attack+1,attack+1+n);

    int t = 1;
    for(int i = 1;i <= m;i++) {
        while(attack[t] <= defend[i] || v[t] == true) {
            t++;
        }
//        cout << "t=" << t << " attack:" << i << " attack[t]=" << attack[t] << " defend[i]=" << defend[i] << endl;
        v[t] = true;
    }

    for(int i = 1;i <= n;i++) {
        // if(v[i] == false)
        // cout << "i=" << i << " attack[i]=" << attack[i] << endl;
        ans += v[i] == false ? attack[i] : 0;
    }

    cout << ans;

    return 0;
}