#include <algorithm>
#include <iostream>
using namespace std;
typedef long long ll;
typedef pair<ll, int> P;

const ll INF = 100000000000;

ll dp[200002][2];

int main()
{
    int n, m;
    cin >> n >> m;
    P p[400002];
    for(int i = 0; i < n; i++){
        ll a;
        cin >> a;
        p[i] = P(a, 0);
    }
    for(int i = 0; i < m; i++){
        ll b;
        cin >> b;
        p[i + n] = P(b, 1);
    }
    p[n + m] = P(-INF, 0);
    sort(p, p + n + m + 1);
    int c = 0;
    for(int i = 1; i <= n + m; i++){
        if(p[i].second){
            c++;
            dp[c][0] = dp[c - 1][0] + p[i].first - p[i - 1].first;
            dp[c][1] = min(dp[c - 1][1] + p[i].first - p[i - 1].first, dp[c - 1][0]);
        }
        else{
            dp[c][0] = min(dp[c][0], dp[c][1] + p[i].first - p[i - 1].first);
            dp[c][1] = dp[c][0];
        }
    }
    cout << dp[c][0] << endl;
}