a=input()
b=input()
c=int(a)
d=int(b)
if 12345<c or 12345<d:
    print("NG")
elif 2<=len(a) and a[0]==0:
    print("NG")
elif 2<=len(b) and b[0]==0:
    print("NG")
elif a.isdigit() and b.isdigit():
    print("OK")
else:
    print("NG")