50pts 求助！！！

#include<bits/stdc++.h>
//#define getchar() (p1==p2&&(p2=(p1=buf)+fread(buf,1,1<<20,stdin),p1==p2)?EOF:*p1++)
using namespace std;
char buf[1<<20],*p1,*p2;
inline int read()
{
	int re=0,ad=1;
	char c=getchar();
	while(c<'0'||c>'9')
	{
		if(c=='-')
			ad=-1;
		c=getchar();
	}
	while(c>='0'&&c<='9')
	{
		re=(re<<3)+(re<<1)+(c^48);
		c=getchar();
	}
	return re*ad;
}
inline void write(int wr)
{
    if(wr<0)
        putchar('-'),wr=-wr;
    if(wr>9)
        write(wr/10);
    putchar(wr%10+'0');
    return;
}
int dp[5555][5555],a[114514],b[114514];
int n;
int main()
{
	n=read();
	for(int i=1;i<=n;i++) cin>>a[i];
	for(int i=1;i<=n;i++) cin>>b[i];
	for(int i=1;i<=n;i++) 
		for(int j=1;j<=n;j++)
		{
			dp[i][j]=max(dp[i-1][j],dp[i][j]);
			if(a[i]==b[j])
			dp[i][j]=max(dp[i][j],dp[i-1][j-1]+1);
		}
	write(dp[n][n]);
    return 0;
}