A=raw_input()
B=raw_input()

def ABproblem(num):
    c=0
    for a in num:
        if ord(a) < ord('0') or ord('9') < ord(a):
            return False
        elif c<4 and a=='0' and len(num)!=1:
            return False
        c+=1
    if int(num)<=12345:
        return True

if ABproblem(A) and ABproblem(B):
    print 'OK'
else:
    print 'NG'