/*
Author: SJ

general
1.shuzu buyao kai xiaole
2.0 1 zhe liangge tepan
3.dfs jide biaoji qidian

str
1.yongle s.substr(), jide kanyixiashibushikeyi yigeyige shuchu

think twice, code once.

*/
#include <bits/stdc++.h>
const int N = 1e5 + 10;
const int INF = 1e9;
using ll = long long;

int n, m, a[100010];
ll ans;
void bsearch(int x) {
	int l = 0, r = n - 1, mark = 0;
	while (l <= r) {
		int mid = l + r >> 1;
		if (a[mid] >= x) {
			mark = mid;
			r = mid - 1;
		} else l = mid + 1;
	}
	int y = std::abs(a[mark] - x), z = std::abs(a[mark - 1] - x);
	ans += std::min(y, z);
}
int main() {
	std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
    
    std::cin >> n >> m;
    for (int i = 0; i < n; i++) std::cin >> a[i];
    std::sort(a, a + n);
    for (int i = 0; i < m; i++) {
    	int b;
    	std::cin >> b;
    	bsearch(b);
    }
    std::cout << ans;
	return 0;
}