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 C++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include<bits/stdc++.h>
using namespace std;
/*
#ifndef ONLINE_JUDGE
    #define cin f
    #define cout g
    ifstream cin("a.in");
    ofstream cout("a.out");
#endif
*/
int k;
char a[3002],b[3002],S[3002],D[3002][3002];
int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
    cin>>(a+1)>>(b+1);
    int N=strlen(a+1);
    int M=strlen(b+1);
    for(int i=1;i<=N;++i)
        for(int j=1;j<=M;++j) D[i][j]=(a[i]==b[j]?1+D[i-1][j-1]:max(D[i-1][j],D[i][j-1]));
    for(int i=N,j=M;i;)
        if(a[i]==b[j]) S[++k]=a[i],--i,--j;
        else D[i-1][j]<D[i][j-1]?--j:--i;
    for(int i=k;i;--i) cout<<S[i];
    return 0;
}