#include <iostream>
#include <vector>
#include <algorithm>
#include <array>
#include <iterator>
#include <string>
#include <cctype>
#include <cstring>
#include <cstdlib>
#include <cassert>
#include <cmath>
#include <ctime>
#include <iomanip>
#include <numeric>
#include <stack>
#include <queue>
#include <map>
#include <unordered_map>
#include <set>
#include <unordered_set>
#include <bitset>
#include <random>
#include <utility>
#include <functional>
#include <chrono>
using namespace std;
void Main()
{
	int N,Q;
	cin >> N >> Q;
	vector<int> A(N),B(Q);
	vector<int> comp;
	comp.reserve(N + Q);
	for(int i = 0;i < N;i++)
	{
		cin >> A[i];
		comp.push_back(A[i]);
	}
	for(int i = 0;i < Q;i++)
	{
		cin >> B[i];
		comp.push_back(B[i]);
	}
	sort(comp.begin(),comp.end());
	comp.erase(unique(comp.begin(),comp.end()), comp.end());
	vector<vector<int>> G(comp.size() + 1);
	for(int i = 0;i < N;i++)
	{
		int id = lower_bound(comp.begin(),comp.end(),A[i]) - comp.begin();
		G[id].push_back(i);
	}
	G[comp.size()].push_back(0);
	int cur = comp.size();
	vector<int> dp(1, 0);
	for(int q = 0;q < Q;q++)
	{
		int nxt = lower_bound(comp.begin(),comp.end(), B[q]) - comp.begin();
		vector<int> n_dp(G[nxt].size(), (int)1e9);
		int j = 0;
		for(int i = 0;i < (int)G[nxt].size();i++)
		{
			while(j < G[cur].size() && G[cur][j] < G[nxt][i])
			{
				j++;
			}
			
			if(j > 0)
			{
				n_dp[i] = min(n_dp[i], dp[j - 1] + G[nxt][i] - G[cur][j - 1]);
			}
			
			if(j < (int)G[cur].size())
			{
				n_dp[i] = min(n_dp[i], dp[j] + G[cur][j] - G[nxt][i]);
			}
		}
		swap(n_dp,dp);
		swap(nxt, cur);
	}
	int ans = (int)1e9;
	for(int i = 0;i < (int)dp.size();i++)
	{
		ans = min(ans, dp[i]);
	}
	cout << ans << "\n";
}
int main()
{
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	int tt = 1;
	/* cin >> tt; */
	while(tt--) Main();
}