#include<bits/stdc++.h>
using namespace std;
int read() {
	int x = 0, f = 1;
	char ch=getchar();
	while(ch<'0' || ch>'9') {
		if(ch == '-') {
			f = -1;
		}
		ch = getchar();
	}
	while(ch>='0' && ch<='9') {
		x = x * 10 + ch - 48;
		ch = getchar();
	}
	return x * f;
}
bool flag;
long long ans;
int q, l, r, mid, n, m, sch[100086], stu[100086];
int main() {
	n = read();
	m = read();
	for(int i=1; i<=n; ++i) {
		sch[i] = read();
	}	
	for(int i=1; i<=m; ++i) {
		stu[i] = read();
	}
	sort(sch+1, sch+1+n);
	for(int i=1; i<=m; ++i) {
		q = stu[i];
		if(q <= sch[1]) {
			ans += sch[1] - q;
			continue;
		} else if(q >= sch[n]) {
			ans += q - sch[n];
			continue;
		}
		flag = false;
		l = 1;
		r = m;
		while(l < r) {
			mid = (l + r)/2;
			if(q == sch[mid]) {
				flag = true;
				break;
			} else if(q < sch[mid]) {
				r = mid;
			} else if(q > sch[mid]) {
				l = mid + 1;
			}
		}
		if(flag) {
			continue;
		}
		if(abs(sch[l-1]-q) < abs(sch[l]-q)) {
			ans += abs(sch[l-1]-q);
		} else {
			ans += abs(sch[l]-q);
		}
	}
	printf("%lld", ans);
	return 0;
}