A=input()
B=input()
if A.isdigit()==True and B.isdigit()==True:
    if int(A)<=12345 and int(B)<=12345:
        if (len(A)>1 and str(A[0])=="0") or (len(B)>1 and str(B[0])=="0"):
            print("NG")
        else:
            print("OK")
    else:
        print("NG")
else:
    print("NG")