#include<bits/stdc++.h>
#include<atcoder/all>
#define rep(i,n) for(int i=0;i<n;i++)
using namespace std;
using namespace atcoder;
typedef long long ll;
typedef vector<int> vi;
typedef vector<long long> vl;
typedef vector<vector<int>> vvi;
typedef vector<vector<long long>> vvl;
typedef long double ld;
typedef pair<int, int> P;

ostream& operator<<(ostream& os, const modint& a) {os << a.val(); return os;}
template <int m> ostream& operator<<(ostream& os, const static_modint<m>& a) {os << a.val(); return os;}
template <int m> ostream& operator<<(ostream& os, const dynamic_modint<m>& a) {os << a.val(); return os;}
template<typename T> istream& operator>>(istream& is, vector<T>& v){int n = v.size(); assert(n > 0); rep(i, n) is >> v[i]; return is;}
template<typename U, typename T> ostream& operator<<(ostream& os, const pair<U, T>& p){os << p.first << ' ' << p.second; return os;}
template<typename T> ostream& operator<<(ostream& os, const vector<T>& v){int n = v.size(); rep(i, n) os << v[i] << (i == n - 1 ? "\n" : " "); return os;}
template<typename T> ostream& operator<<(ostream& os, const vector<vector<T>>& v){int n = v.size(); rep(i, n) os << v[i] << (i == n - 1 ? "\n" : ""); return os;}

template<typename T> void chmin(T& a, T b){a = min(a, b);}
template<typename T> void chmax(T& a, T b){a = max(a, b);}

struct Edge_BFS01{
	int from, to;
	int cost;
	Edge_BFS01(int from, int to, int cost) : from(from), to(to), cost(cost) {};
};

const int INF = 1001001001;
struct BFS01{
	int n, m;
	vector<bool> initialized;
	vector<Edge_BFS01> E;
	vector<vector<int>> G;
	map<int, vector<int>> dist;
	map<int, vector<int>> idx;
	BFS01(int _n) : n(_n), m(0), initialized(n, false), G(n){}
	void add_edge(int from, int to, int cost){
		assert(cost == 0 or cost == 1);
		Edge_BFS01 e(from, to, cost);
		E.push_back(e);
		G[from].emplace_back(m);
		m++;
	}
	void calc(int s){
		initialized[s] = true;
		dist[s] = vector<int>(n, INF);
		idx[s] = vector<int>(n, -1);
		deque<tuple<int, int ,int>> de;
		de.emplace_back(0, s, -1);
		while(de.size()){
			auto [cost, from, index] = de.front(); de.pop_front();
			if(dist[s][from] <= cost) continue;
			dist[s][from] = cost;
			idx[s][from] = index;
			for(int index : G[from]){
				int to = E[index].to;
				int cost_plus = E[index].cost;
				if(dist[s][to] <= cost + cost_plus) continue;
				if(cost_plus == 0) de.emplace_front(cost + cost_plus, to, index);
				if(cost_plus == 1) de.emplace_back(cost + cost_plus, to, index);
			}
		}
	}
	int get_dist(int s, int t){
		if(!initialized[s]) calc(s);
		return dist[s][t];
	}
};

int main(){
	int n, q;
	cin >> n >> q;
	vector<int> a(n);
	vector<int> b(q);
	cin >> a >> b;
	BFS01 graph(n * q + 1);
	int tv = n * q;
	rep(j, q){
		rep(i, n - 1){
			graph.add_edge(j * n + i, j * n + (i + 1), 1);
			graph.add_edge(j * n + (i + 1), j * n + i, 1);
		}
		rep(i, n){
			if(a[i] == b[j]){
				if(j != q - 1) graph.add_edge(j * n + i, (j + 1) * n + i, 0);
				else graph.add_edge(j * n + i, tv, 0);
			}
		}
	}
	int ans = graph.get_dist(0, tv);
	cout << ans << "\n";
	return 0;
}