/********************************************************************************
*                  -> Bismillahir Rahmanir Rahim <-                             *
*                                                                               *
*                                                                               *
* __________               .___          .__                  ____  ________    *
* \______   \ _____      __| _/   ______ |  |__   _____      /_   | \_____  \   *
*  |    |  _/ \__  \    / __ |   /  ___/ |  |  \  \__  \      |   |  /  ____/   *
*  |    |   \  / __ \_ / /_/ |   \___ \  |   Y  \  / __ \_    |   | /       \   *
*  |______  / (____  / \____ |  /____  > |___|  / (____  /    |___| \_______ \  *
*         \/       \/       \/       \/       \/       \/                   \/  *
*                                                                               *
*              .=.,                                                             *
*             ;c =\                                                             *
*           __|  _/                                                             *
*         .'-'-._/-'-._                                                         *
*        /..   ____    \                                                        *
*       /' _  [<BF>] )  \                                                       *
*      (  / \--\_>/-/'._ )                                                      *
*       \-;_/\__;__/ _/ _/                                                      *
*        '._}|==o==\{_\/                                                        *
*         /  /-._.--\  \_                                                       *
*        // /   /|   \ \ \                                                      *
*       / | |   | \;  |  \ \                                                    *
*      / /  | :/   \: \   \_\                                                   *
*     /  |  /.'|   /: |    \ \                                                  *
*     |  |  |--|   |--|     \_\                                                 *
*     / _/   \ |   | /___--._) \                                                *
*    |_(---'-| >   | |       '-'                                                *
*           /_/     \_\                                                         *
*                                                                               *
 *******************************************************************************/
#include<bits/stdc++.h>
using namespace std;

#define pi acos(-1)
typedef  long long ll;
typedef  unsigned long long ull;
typedef  unsigned un;

//defined taking input;
#define sf           scanf
#define si(a)        sf("%d",&a)
#define sc(a)        sf("%c",&a)
#define sii(a,b)     sf("%d %d",&a,&b)
#define siii(a,b,c)  sf("%d %d %d",&a,&b,&c)
#define sl(a)        sf("%lld",&a)
#define sll(a,b)     sf("%lld %lld",&a,&b);
#define slll(a,b,c)  sf("%lld %lld %lld",&a,&b,&c);

#define pf           printf
#define pfi(a)       pf("%d\n",a)
#define pfl(a)       pf("%ld\n",a)
#define pfn          pf("\n")
#define pfyes        pf("YES\n")
#define pfno         pf("NO\n")
#define pfYes        pf("Yes\n")
#define pfNo         pf("No\n")

#define wh            while
#define wht(t)        while(t--)


int main()
{
    //freopen("input","r",stdin);

    int k,a,b;
    siii(k,a,b);

    int last = (b/k)*k;
    if(a<=last){
        pf("OK\n");
    }
    else{
        pf("NG\n");
    }

    return 0;
}


Measured memory_bytes: 3740