#include<bits/stdc++.h>
using namespace std;
#define V vector
#define pb push_back
const int INF = 2e9 + 100;
void solve() {
    int n, m; cin >> n >> m;
    V<int> a(n + 1);
    V<int> b(m + 1);
    for(int i = 1; i <= n; i++) cin >> a[i];
    for(int i = 1; i <= m; i++) cin >> b[i];

    if(m > n) swap(m, n), swap(a, b);

    V<V<int>> dp(n + 2, V<int>(m + 2, INF / 2));
    dp[1][1] = 0;

    for(int i = 1; i <= n; i++) {
        for(int j = 1; j <= m; j++) {
            if(a[i] == b[j] || a[i] == 1 || b[j] == 1) {
                dp[i + 1][j + 1] = min(dp[i][j], dp[i + 1][j + 1]);
            }
            dp[i + 1][j] = min(dp[i][j] + 1, dp[i + 1][j]);
            dp[i][j + 1] = min(dp[i][j] + 1, dp[i][j + 1]);
        }
    }

    int ans = INF;

    for(int i = 1; i <= n + 1; i++) {   
        ans = min(ans, dp[i][m + 1]);
    }
    for(int i = 1; i <= m + 1; i++) {   
        ans = min(ans, dp[n + 1][i]);
    }
    cout << ans << endl;
}

int main() {
    ios::sync_with_stdio(0), cin.tie(0);
    int t = 1; 
    // cin >> t;
    while(t--) solve();
}