#include <bits/stdc++.h>
using namespace std;
using i64 = long long;
#define all(x) x.begin(), x.end()
void solve()
{
    int n, m;
    cin >> n >> m;
    vector<int> a(n), b(m);
    for (int i = 0; i < n; i++)
        cin >> a[i];
    for (int i = 0; i < m; i++)
        cin >> b[i];
    reverse(all(a));
    reverse(all(b));
    auto work = [&](vector<int> &a, vector<int> &b)
    {
        int n = a.size(), m = b.size();
        vector<vector<int>> dp(n + 1, vector<int>(m + 1, 1e6));
        // 匹配完成m个最小的cost
        for (int i = 0; i <= n; i++)
            dp[i][0] = i;
        for (int i = 0; i <= m; i++)
            dp[0][i] = i;
        for (int i = 0; i < n; i++)
            for (int j = 0; j < m; j++)
            {
                if (a[i] == b[j])
                {
                    dp[i + 1][j + 1] = min({
                        dp[i + 1][j + 1],
                        dp[i][j],
                        dp[i+1][j]+1,
                        dp[i][j+1]+1
                    });
                }
                else
                {
                    dp[i + 1][j + 1] = min({dp[i + 1][j + 1],
                                            dp[i + 1][j] + 1,
                                            dp[i][j + 1] + 1});
                }
            }
        int res=1e6;
        for(int i=0;i<=n;i++)res=min(dp[i][m],res);
        for(int i=0;i<=m;i++)res=min(dp[n][i],res);
        return res;
    };
    cout<<work(a,b)<<endl;
}
signed main()
{
    ios::sync_with_stdio(false);
    cin.tie(0), cout.tie(0);
    int T = 1;
    while (T--)
        solve();
}