output_description: 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.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      s
      t
attempt: s, t = [tuple(input()) for u in (1, 1)]
  l, li = [["" for i in range(len(s) + 1)] for j in (1, 1)]
  f = 0
  for j in range(len(t)):
      for i in range(len(s)):
          if f:
              if t[j] == s[i]:
                  l[i + 1] = li[i] + t[j]
              else:
                  l[i + 1] = li[i + 1] if len(li[i + 1]) > len(l[i]) else l[i]
          else:
              if t[j] == s[i]:
                  li[i + 1] = l[i] + t[j]
              else:
                  li[i + 1] = l[i + 1] if len(l[i + 1]) > len(li[i]) else li[i]
          f = (f + 1) % 2
  print(li[-1] if f else l[-1])
  
problem_description: Statement
  
  You are given strings s and t. Find one longest string that is a subsequence
  of both s and t.
samples: [{"input": "axyb\n    abyxb", "output": "axb\n    \n\nThe answer is `axb` or `ayb`; either will be accepted.\n\n* * *"}, {"input": "aa\n    xayaz", "output": "aa\n    \n\n* * *"}, {"input": "a\n    z", "output": "The answer is `` (an empty string).\n\n* * *"}, {"input": "abracadabra\n    avadakedavra", "output": "aaadara"}]