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

bool Memory_begin;

bool Memory_end;

signed main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    cerr << (&Memory_end - &Memory_begin) / 1048576.0 << "MB" << '\n';

    int n, m;
    cin >> n >> m;
    vector<int> a(n), b(m);
    for (int &i : a)
        cin >> i;
    for (int &i : b)
        cin >> i;
    vector dp(n + 1, vector<int>(m + 1, 1e9));
    dp[n][m] = 0;
    int ans = 1e9;
    for (int i = n; i >= 0; i--)
    {
        for (int j = m; j >= 0; j--)
        {
            if (!i or !j)
            {
                ans = min(ans, dp[i][j]);
                continue;
            }
            if (a[i - 1] == b[j - 1])
                dp[i - 1][j - 1] = min(dp[i - 1][j - 1], dp[i][j]);
            dp[i - 1][j] = min(dp[i - 1][j], dp[i][j] + 1);
            dp[i][j - 1] = min(dp[i][j - 1], dp[i][j] + 1);
        }
    }
    cout << ans << '\n';
}
/*
 */