/*************************************
* author: marvinthang *
* created: 24.06.2023 11:57:30 *
*************************************/
#include "wiring.h"
#include <bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define left ___left
#define right ___right
#define TIME (1.0 * clock() / CLOCKS_PER_SEC)
#define MASK(i) (1LL << (i))
#define BIT(x, i) ((x) >> (i) & 1)
#define __builtin_popcount __builtin_popcountll
#define ALL(v) (v).begin(), (v).end()
#define REP(i, n) for (int i = 0, _n = (n); i < _n; ++i)
#define REPD(i, n) for (int i = (n); i--; )
#define FOR(i, a, b) for (int i = (a), _b = (b); i < _b; ++i)
#define FORD(i, b, a) for (int i = (b), _a = (a); --i >= _a; )
#define FORE(i, a, b) for (int i = (a), _b = (b); i <= _b; ++i)
#define FORDE(i, b, a) for (int i = (b), _a = (a); i >= _a; --i)
#define scan_op(...) istream & operator >> (istream &in, __VA_ARGS__ &u)
#define print_op(...) ostream & operator << (ostream &out, const __VA_ARGS__ &u)
#ifdef LOCAL
#include "debug.h"
#else
#define file(name) if (fopen(name".inp", "r")) { freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout); }
#define DB(...) 23
#define db(...) 23
#define debug(...) 23
#endif
template <class U, class V> scan_op(pair <U, V>) { return in >> u.first >> u.second; }
template <class T> scan_op(vector <T>) { for (size_t i = 0; i < u.size(); ++i) in >> u[i]; return in; }
template <class U, class V> print_op(pair <U, V>) { return out << '(' << u.first << ", " << u.second << ')'; }
template <size_t i, class T> ostream & print_tuple_utils(ostream &out, const T &tup) { if constexpr(i == tuple_size<T>::value) return out << ")"; else return print_tuple_utils<i + 1, T>(out << (i ? ", " : "(") << get<i>(tup), tup); }
template <class ...U> print_op(tuple<U...>) { return print_tuple_utils<0, tuple<U...>>(out, u); }
template <class Con, class = decltype(begin(declval<Con>()))> typename enable_if <!is_same<Con, string>::value, ostream&>::type operator << (ostream &out, const Con &con) { out << '{'; for (__typeof(con.begin()) it = con.begin(); it != con.end(); ++it) out << (it == con.begin() ? "" : ", ") << *it; return out << '}'; }
template <class A, class B> bool minimize(A &a, B b) { if (a > b) { a = b; return true; } return false; }
template <class A, class B> bool maximize(A &a, B b) { if (a < b) { a = b; return true; } return false; }
// end of template
const int INF = 1e9 + 7;
long long min_total_length(vector <int> r, vector <int> b) {
vector <pair <int, int>> p;
p.emplace_back(-INF, 0);
for (int x: r) p.emplace_back(x, 0);
for (int x: b) p.emplace_back(x, 1);
int n = (int) p.size() - 1;
sort(ALL(p));
p[0].se = p[1].se ^ 1;
vector <long long> dp(n + 1, 1e18);
dp[0] = 0;
for (int cur = 1, nxt = 1, prv = 0; cur <= n; ) {
while (nxt <= n && p[nxt].se == p[cur].se) ++nxt;
FOR(i, prv, cur) minimize(dp[i], dp[i - 1] + p[cur].fi - p[i].fi);
long long s = 0;
for (int i = cur, j = cur - 1; i < nxt && j >= prv; ++i, --j) {
s += p[i].fi - p[j].fi;
minimize(dp[i], (j ? dp[j - 1] : 0) + s);
}
FOR(i, cur, nxt) minimize(dp[i], dp[i - 1] + p[i].fi - p[cur - 1].fi);
prv = cur;
cur = nxt;
}
return dp[n];
}
#ifdef LOCAL
#include "wiring.h"
#include <cassert>
#include <cstdio>
using namespace std;
int main() {
file("wiring");
int n, m;
assert(2 == scanf("%d %d", &n, &m));
vector<int> r(n), b(m);
for(int i = 0; i < n; i++)
assert(1 == scanf("%d", &r[i]));
for(int i = 0; i < m; i++)
assert(1 == scanf("%d", &b[i]));
long long res = min_total_length(r, b);
printf("%lld\n", res);
return 0;
}
#endif
