def num(x):
    if x=="1":
        return 1
    elif x=="2":
        return 1
    elif x=="3":
        return 1
    elif x=="4":
        return 1
    elif x=="5":
        return 1
    elif x=="6":
        return 1
    elif x=="7":
        return 1
    elif x=="8":
        return 1
    elif x=="9":
        return 1
    elif x=="0":
        return 1
    else:
        return 0
def nuli (l):
    n=1
    i=0
    while n==1 and i < len(l):
        if num(l[i])==0:
            n=0
        i+=1
    if len(l)>1 and l[0]=="0":
         n=0
    return n
A=list(input())
B=input()
#print(nuli(B))
if nuli (A)==0 or nuli(B)==0:
    print ("NG")
else:
    Bi=int(B)
    if 0<=Bi and Bi<12346:
        print ("OK")
    else:
        print ("NG")