#include <bits/stdc++.h>
using namespace std;
#define int long long
#define x first
#define y second
#define LL long long
typedef pair<int,int> PII;
int dx[] = {-1, 1, 0, 0};
int dy[] = {0, 0, -1, 1};
const int N = 1e6 + 10, MOD = 1e9 + 10;
int a[N], b[N];
int n, m, res;

int ef1(int x)
{
    int l = 1, r = n;
    while( r > l )
    {
        int mid = l + r >> 1;
        if( a[mid] >= x )    r = mid;
        else    l = mid + 1;
    }
    return a[l];
}

int ef2(int x )
{
    int l = 1, r = n;
    while( r > l )
    {
        int mid = l + r + 1 >> 1;
        if( a[mid] <= x )   l = mid;
        else    r = mid - 1;
    }
    return a[l];
}
void solve()
{
    
    cin >> n >> m;
    for(int i = 1; i <= n; i ++ )   cin >> a[i];
    for(int i = 1; i <= m; i ++ )   cin >> b[i];
    sort(a+1, a+1+n);
    a[0] = -1, a[m+1] = 1e9;
    for(int i = 1; i <= m; i ++ )
        res += min(abs(b[i]-ef1(b[i])), abs(b[i]-ef2(b[i])));
    cout << res;
}
signed main()
{
    solve();
    return 0;
}