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++ (GCC 9.2.1) (judge verdict: Wrong Answer)

#include<bits/stdc++.h>
#define ll long long
using namespace std;
string s,t;
ll solve(int i,int j,string &ans){
  if(i>=s.size()||j>=t.size()){
    ans+='\0';
    return 0;
  }
  ll l=0;
  if(s[i]==t[j]){
   ans+=s[i];
   l=1+solve(i+1,j+1,ans);
  }
  else{
    l=max(solve(i,j+1,ans),solve(i+1,j,ans));
  }
  return l;
}

int main(){

cin>>s>>t;
string ans="";
ll a=solve(0,0,ans);
cout<<ans;
return 0;
}