import sys
input=lambda: sys.stdin.readline().rstrip()
N=[str(i) for i in range(10)]
def chk(x):
  ret=True
  for xx in x:
    if xx not in N:
      ret=False
  if x[0]=="0" and len(x)>1:
    ret=False
  if ret and int(x)>12345:
    ret=False
  return ret
a=chk(input())
b=chk(input())
print("OK" if a and b else "NG")