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 Python (3.4.3) (judge verdict: Time Limit Exceeded)

s=list(input())
t=list(input())
dp=[[0 for i in range(len(t)+1)] for j in range(len(s)+1)]
for i in range(len(s)):
    for j in range(len(t)):
        if s[i]==t[j]:
            dp[i+1][j+1]=max(dp[i][j]+1,dp[i+1][j+1])
        dp[i][j+1]=max(dp[i][j],dp[i][j+1])
        dp[i+1][j]=max(dp[i][j],dp[i+1][j])
ans=[]
i=len(s)
j=len(t)
while(i>0 and j>0):
    if dp[i][j]==dp[i-1][j]:
        i-=1
    elif dp[i][j]==dp[i][j-1]:
        j-=1
    else:
        ans.append(s[i-1])
        i-=1
        j-=1
print("".join(ans[::-1]))