def n(s):
  return sum([x not in '0123456789' for x in s])<1
z=lambda x:not(x[0]=='0' and len(x)>1)
m=12346
v='NG'
a=input()
b=input()
if n(a+b):
  if int(a)<m and int(b)<m:
    if z(a)&z(b):
      v='OK'
print(v)