// https://qoj.ac/contest/1464/problem/7990
#include <bits/stdc++.h>
#define ll long long
using namespace std;
const int N = 2e3 + 5;
int m, n;
int p[N], q[N];
int dp[N][N]; // dp[i][j]表示从p[a] q[b]开始向前，满足条件的插入1的最少数量
int dfs(int a, int b) {
    if (dp[a][b]) return dp[a][b];
    if (a == 0 || b == 0) {
        return 0;
    }
    if (p[a] == p[b] || p[a] == 1 || p[b] == 1)
        dp[a][b] = dfs(a - 1, b - 1);
    else {
        int x = dfs(a - 1, b) + 1;
        int y = dfs(a, b - 1) + 1;
        dp[a][b] = min(x, y);
    }
    return dp[a][b];
}
int main()
{
    ios::sync_with_stdio(false), cin.tie(0), cout.tie(0);
    cin >> m >> n;
    for (int i = 1; i <= m; i++) {
        cin >> p[i];
    }
    for (int i = 1; i <= n; i++) {
        cin >> q[i];
    }
    cout << dfs(m, n) << endl;
    // for (int i = 1; i <= m; i++) {
    //     for (int j = 1; j <= n; j++) {
    //         cout << dp[i][j] << " ";
    //     }
    //     cout << endl;
    // }
}