import strutils, sequtils

when isMainModule:
  var
    a = stdin.readLine
    b = stdin.readLine

  for c in a:
    if c in 'a'..'z' or c in 'A'..'Z':
      echo "NG"
      quit()
  for c in b:
    if c in 'a'..'z' or c in 'A'..'Z':
      echo "NG"
      quit()

  if (a.len > 1 and a[0] == '0') or (b.len > 1 and b[0] == '0'):
    echo "NG"
    quit()

  if a.parseInt > 12345 or b.parseInt > 12345:
    echo "NG"
    quit()

  echo "OK"