#include <fstream>

using namespace std;
ifstream fin("cmlsc.in");
ofstream fout("cmlsc.out");
const int dim =  1024 + 5;
int a[dim], b[dim], dp[dim][dim], n, m;
int main()
{
    int i, j;
    fin >> n >> m;
    for ( i = 1; i <= n; ++i )
        fin >> a[i];
    for ( i = 1; i <= m; ++i )
        fin >> b[i];

    for ( i = 1; i <= n; ++i )
        for ( j = 1; j <= m; ++j )
        {
            if ( a[i] == b[j] )
                dp[i][j] = dp[i - 1][j - 1] + 1;
            else
                dp[i][j] = max(dp[i - 1][j], dp[i][j - 1]);
        }

    fout << dp[n][m] << '\n';
    return 0;
}