import sys

read = sys.stdin.buffer.read

readline = sys.stdin.buffer.readline

readlines = sys.stdin.buffer.readlines

sys.setrecursionlimit(10 ** 7)



k = int(readline())

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

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

    if i % k == 0:

        print('OK')

        exit()

print('NG')

import sys

read = sys.stdin.buffer.read

readline = sys.stdin.buffer.readline

readlines = sys.stdin.buffer.readlines

sys.setrecursionlimit(10 ** 7)



k, a, b = list(map(int, read().split()))

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

    if i % k == 0:

        print('OK')

        exit()

print('NG')

import sys

read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines
sys.setrecursionlimit(10**7)
k = int(readline())
a, b = list(map(int, readline().split()))
for i in range(a, b + 1):
    if i % k == 0:
        print("OK")
        exit()
print("NG")

import sys

read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines
sys.setrecursionlimit(10**7)
k, a, b = list(map(int, read().split()))
for i in range(a, b + 1):
    if i % k == 0:
        print("OK")
        exit()
print("NG")

-k = int(readline()) -a, b = list(map(int, readline().split())) +k, a, b = list(map(int, read().split()))