#include <bits/stdc++.h>
using namespace std;

struct Edge {
    int to;
    long long cost;
};

struct Dijkstra {
    vector<vector<Edge>> g;
    int n, x;
    vector<long long> dist;
    vector<int> prev;
    
    Dijkstra(vector<vector<Edge>> g_, int x_) : g(g_), n(g.size()), x(x_), dist(n, 1000000000000000000), prev(n) {
        build();
    }
    
    void build() {
        vector<bool> visit(n, false);
        priority_queue<pair<long long, int>, vector<pair<long long, int>>, greater<pair<long long, int>>> que;
        dist[x] = 0LL;
        que.push({dist[x], x});
        while (!que.empty()) {
            int v = que.top().second;
            que.pop();
            if (visit[v]) {
                continue;
            }
            visit[v] = true;
            for (auto e : g[v]) {
                int nv = e.to;
                long long d = e.cost;
                if (dist[nv] > dist[v] + d) {
                    dist[nv] = dist[v] + d;
                    prev[nv] = v;
                    que.push({dist[nv], nv});
                }
            }
        }
    }
    
    long long getdist(int y) {
        return dist[y];
    }
    
    vector<int> getroute(int y) {
        int cur = y;
        vector<int> res = {cur};
        while (cur != x) {
            cur = prev[cur];
            res.push_back(cur);
        }
        reverse(res.begin(), res.end());
        return res;
    }
};

int main() {
    int n, q;
    cin >> n >> q;
    vector<int> a(n), b(q);
    for (int i = 0; i < n; i++) {
        cin >> a[i];
    }
    for (int i = 0; i < q; i++) {
        cin >> b[i];
    }
    //(i, j) クエリをi個処理して現在jにいる
    vector<vector<Edge>> g((q + 1) * n);
    for (int i = 0; i <= q; i++) {
        for (int j = 0; j < n - 1; j++) {
            //(i, j) <-> (i, j+1)
            g[n * i + j].push_back({n * i + j + 1, 1LL});
            g[n * i + j + 1].push_back({n * i + j, 1LL});
        }
    }
    for (int i = 1; i <= q; i++) {
        for (int j = 0; j < n; j++) {
            //(i-1, j-1) -> (i, j) (cost 1)
            //(i-1, j)   -> (i, j) (cost 0)
            //(i-1, j+1) -> (i, j) (cost 1)
            if (b[i - 1] == a[j]) {
                if (j >= 1) {
                    g[n * (i - 1) + j - 1].push_back({n * i + j, 1LL});
                }
                g[n * (i - 1) + j].push_back({n * i + j, 0LL});
                if (j < n - 1) {
                    g[n * (i - 1) + j + 1].push_back({n * i + j, 1LL});
                }
            }
        }
    }
    Dijkstra D(g, 0);
    long long ans = 1000000000000000000;
    for (int j = 0; j < n; j++) {
        ans = min(ans, D.getdist(n * q + j));
    }
    cout << ans << endl;
}