import strutils
proc echoNG = echo "NG"; quit()

let A, B = stdin.readLine

for AorB in [A, B]:
  if not AorB.isDigit:
    echoNG()
  elif AorB.parseInt > 12345:
    echoNG()
  elif AorB.len != 1 and AorB[0] == '0':
    echoNG()

echo "OK"