Problem:
Score : 100 points

Problem Statement

You are given strings s and t.
Find one longest string that is a subsequence of both s and t.

Notes

A subsequence of a string x is the string obtained by removing zero or more characters from x and concatenating the remaining characters without changing the order.

Constraints

s and t are strings consisting of lowercase English letters.

1 \leq |s|, |t| \leq 3000

Input

Input is given from Standard Input in the following format:

s
t

Output

Print one longest string that is a subsequence of both s and t.
If there are multiple such strings, any of them will be accepted.

Sample Input 1

axyb
abyxb

Sample Output 1

axb

The answer is axb or ayb; either will be accepted.

Sample Input 2

aa
xayaz

Sample Output 2

aa

Sample Input 3

a
z

Sample Output 3

The answer is (an empty string).

Sample Input 4

abracadabra
avadakedavra

Sample Output 4

aaadara

Solution in Pascal (FPC 2.6.2) (judge verdict: Wrong Answer)

var
	s,t,ans:ansistring;
	i,j,n,m:longint;
	a:array[0..3001,0..3001] of longint;
begin
	readln(s); n:=length(s);
	readln(t); m:=length(t);
	fillchar(a,sizeof(a),0);
	for i:=1 to n do
		for j:=1 to m do
			if s[i]=t[j] then a[i,j]:=a[i-1,j-1]+1
			else if a[i-1,j]>a[i,j-1] then a[i,j]:=a[i-1,j]
					else a[i,j]:=a[i,j-1];
	writeln(a[n,m]);
	ans:='';
	i:=1; j:=1;
	while (i<=n) and (j<=m) do
		if s[i]=t[j] then
		begin
			ans:=ans+s[i];
			inc(i); inc(j);
		end
		else if a[i+1,j]<a[i,j+1] then inc(j)
				else inc(i);
	if ans<>'' then writeln(ans);
end.