#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
int i, j, n, m, dp[5009][5009];
char a[5009], b[5009];
int main()
{
    freopen("cmlsc.in","r",stdin);
    freopen("cmlsc.out","w",stdout);
    scanf("%d%d",&n,&m);
    for(i=1;i<=n;i++)
        scanf("%d",&a[i]);
    for(i=1;i<=m;i++)
        scanf("%d",&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]);
        }
    printf("%d\n",dp[n][m]);
    return 0;
}