#include <iostream>
#include <fstream>
using namespace std;

ifstream fin("titu.in");

int x[30], y[30], m, n, a[30][30] ;

int maxim(int x, int y)
{
    if(x>y)
        return x;
    else
        return y;
}

void citeste()
{
    fin>>m>>n;

    for(int i=1; i<=m; i++)
        fin>>x[i];

    for(int i=1;i<=n;i++)
        fin>>y[i];
    fin.close();
}

void cmls()
{
    int i, j;

    for(i = 0; i<=m; i++)
       a[i][0] = 0;

    for(j=0; j<=n; j++)
        a[0][i] = 0;

    for(i=1;i<=m;i++)
        for(j=1;j<=n;j++)
        {
            if(x[i]==y[j])
                a[i][j] = a[i-1][j-1]+1;
            else
            a[i][j] = maxim(a[i-1][j], a[i][j-1]);
        }
    cout<<a[m][n];

}
int main()
{
    citeste();
    cmls();

    return 0;
}