#include<bits/stdc++.h>

#define Fast ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);

#define int long long

using namespace std;

signed main()

{

Fast

int n,m;

cin>>n>>m;

int mtr[n],mac[m];

for(int i=0;i<n;i++) cin>>mtr[i];

for(int j=0;j<m;j++) cin>>mac[j];

sort(mtr,mtr+n,std::greater<int>());

sort(mac,mac+m,std::greater<int>());

int ans = 0,key = 0;

for(int k=0;k<n;k++)

{

if (mtr[k]<=mac[key])

{

key++;

ans += mtr[k];

if (key == m)

break;

}

}

cout<<ans;

}