A=input()
B=input()

for a in A+B:
    if "0"<=a<="9":
        True
    else:
        print("NG")
        exit()

if A!="0" and A[0]=="0":
    print("NG")
elif B!="0" and B[0]=="0":
    print("NG")
else:
    if 0<=int(A)<=12345 and 0<=int(B)<=12345 :
        print("OK")
    else:
        print("NG")