def is_leading_zero(a):
    if len(a) > 1 and a[0] == "0":
        return True
    else:
        return False

def range_ok(a):
    if 0 <= a <= 12345:
        return True
    else:
        return False

A = input()
B = input()

if is_leading_zero(A) or is_leading_zero(B):
    print("NG")
elif not (A.isdigit() and B.isdigit()):
    print("NG")
elif not (range_ok(int(A)) and range_ok(int(B))):
    print("NG")
else:
    print("OK")