import sequtils, strutils


func `>?`(x, y: char): bool =
  if x == '4' and y == '7': return true
  if x == '7' and y == '4': return false
  return x > y


const
  z = "0000000000"

let
  ab = stdin.readLine.split
var
  a = ab[0]
  b = ab[1]

a = (z & a)[^10..^1]
b = (z & b)[^10..^1]

var
  i = 0

while a[i] == b[i]:
  inc i

echo:
  if a[i] >? b[i]: ab[0]
  else: ab[1]