#include <bits/stdc++.h>

using namespace std;

#define lld long long int
#define ulld unsigned long long int
#define pii pair<int, int>
#define pll pair<lld, lld>
#define pff pair<double, double>

const int dinf = 1e9 + 10;
const lld ldinf = 1e18 + 10;

const int N = 2e3 + 10;
const int M = 998244353;

int n, m;
int a[N], b[N], dp[N][N];

void solve()
{
    cin >> n >> m;
    for (int i = 1; i <= n; i++)
        cin >> a[i];
    for (int j = 1; j <= m; j++)
        cin >> b[j];
    for (int i = 1; i <= n; i++)
        for (int j = 1; j <= n; j++)
        {
            if (a[i] == 1 || b[j] == 1 || a[i] == b[j])
                dp[i][j] = dp[i - 1][j - 1];
            else
                dp[i][j] = min(dp[i - 1][j], dp[i][j - 1]) + 1;
        }
    cout << dp[n][m] << endl;
}

#define debug 0
int main()
{
#if debug
    clock_t start = clock();
    freopen("1.in", "r", stdin);
    freopen("1.out", "w", stdout);
#endif

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

#if debug
    cout << endl << "time: " << clock() - start << endl;
#endif
    return 0;
}