import sys

input = sys.stdin.readline



def main():

    n = int(eval(input()))

    a, b = list(map(int, input().split()))

    flag = False

    for i in range(a,b+1):

        if i % n == 0:

            flag = True

            break



    if flag:

        print('OK')

    else:

        print('NG')



if __name__ == '__main__':

    main()

import sys

input = sys.stdin.readline



def main():

    k = int(eval(input()))

    a, b = list(map(int, input().split()))



    largest = (b // k) * k



    if a <= largest:

        print('OK')

    else:

        print('NG')



if __name__ == '__main__':

    main()

import sys

input = sys.stdin.readline


def main():
    n = int(eval(input()))
    a, b = list(map(int, input().split()))
    flag = False
    for i in range(a, b + 1):
        if i % n == 0:
            flag = True
            break
    if flag:
        print("OK")
    else:
        print("NG")


if __name__ == "__main__":
    main()

import sys

input = sys.stdin.readline


def main():
    k = int(eval(input()))
    a, b = list(map(int, input().split()))
    largest = (b // k) * k
    if a <= largest:
        print("OK")
    else:
        print("NG")


if __name__ == "__main__":
    main()

-    n = int(eval(input())) +    k = int(eval(input())) -    flag = False -    for i in range(a, b + 1): -        if i % n == 0: -            flag = True -            break -    if flag: +    largest = (b // k) * k +    if a <= largest: