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 Fortran (gfortran v4.8.4) (judge verdict: Runtime Error)

program EDPCF
    implicit none
    integer(8)::i,j,slen,tlen,cursor,dp(3100,3100)
    character(3000)::s,t,ans
    read*,s,t
    slen=len_trim(s)
    tlen=len_trim(t)

    dp=0

    do i=1,slen
        do j=1,tlen
            if(s(i:i)==t(j:j))then
                dp(j+1,i+1)=max(dp(j,i)+1,dp(j,i+1),dp(j+1,i))
            else
                dp(j+1,i+1)=max(dp(j,i+1),dp(j+1,i))
            end if
        end do
    end do

    i=slen+1
    j=tlen+1
    cursor=dp(tlen+1,slen+1)

    if(dp(tlen+1,slen+1)>0)then
        do
            if(i<=0.or.j<=0)exit
            if(dp(j,i)==dp(j,i-1))then
                i=i-1
            else if(dp(j,i)==dp(j-1,i))then
                j=j-1
            else
                ans(cursor:cursor)=s(i-1:i-1)
                cursor=cursor-1
                i=i-1
                j=j-1
            end if
        end do

        print'(A)',ans(1:dp(tlen+1,slen+1))
    else
        print'(A)',""
    end if
end program EDPCF