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)

# https://atcoder.jp/contests/dp/tasks/dp_f
import sys
input = sys.stdin.readline

s = input()
t = input()

dp = [[''] * len(t) for _ in range(len(s))]

for i in range(1, len(s)):
    for j in range(1, len(t)):
        res = []
        if s[i - 1] == t[j - 1]:
            dp[i][j] = max(dp[i][j],
                           dp[i - 1][j - 1] + s[i - 1],
                           key=len)
        dp[i][j] = max(dp[i][j], dp[i][j - 1], key=len)
        dp[i][j] = max(dp[i][j], dp[i - 1][j], key=len)

print(dp[len(s) - 1][len(t) - 1])