import java.util.Scanner;
public class Main {
    public static void main(String[] args) throws Exception {
        Scanner stdIn= new Scanner(System.in);
        int k = stdIn.nextInt();
        int a = stdIn.nextInt();
        int b = stdIn.nextInt();
        boolean c=false;
        if(a-b>=k){
            c=true;
        }else{
            for(int i=a;i<=b;i++){
                if(i%k==0){
                   c=true; 
                }
            }
        }
        if(c){
            System.out.println("OK");
        }else{
            System.out.println("NG");
        }
    }
} import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args) throws Exception {
        Scanner stdIn= new Scanner(System.in);
        int k = stdIn.nextInt();
        int a = stdIn.nextInt();
        int b = stdIn.nextInt();
        boolean c=false;
        if(a-b>=k){
            c=true;
        }else{
            for(int i=a;i<=b;i++){
                if(i%k==0){
                   c=true; 
                }
            }
        }
        if(c){
            System.out.println("OK");
        }else{
            System.out.println("NG");
        }
    }
} Main public static void main(String[] args) throws Exception {
        Scanner stdIn= new Scanner(System.in);
        int k = stdIn.nextInt();
        int a = stdIn.nextInt();
        int b = stdIn.nextInt();
        boolean c=false;
        if(a-b>=k){
            c=true;
        }else{
            for(int i=a;i<=b;i++){
                if(i%k==0){
                   c=true; 
                }
            }
        }
        if(c){
            System.out.println("OK");
        }else{
            System.out.println("NG");
        }
    } main {
        Scanner stdIn= new Scanner(System.in);
        int k = stdIn.nextInt();
        int a = stdIn.nextInt();
        int b = stdIn.nextInt();
        boolean c=false;
        if(a-b>=k){
            c=true;
        }else{
            for(int i=a;i<=b;i++){
                if(i%k==0){
                   c=true; 
                }
            }
        }
        if(c){
            System.out.println("OK");
        }else{
            System.out.println("NG");
        }
    } Scanner stdIn= new Scanner(System.in); stdIn new Scanner(System.in) int k = stdIn.nextInt(); k stdIn.nextInt() stdIn.nextInt stdIn int a = stdIn.nextInt(); a stdIn.nextInt() stdIn.nextInt stdIn int b = stdIn.nextInt(); b stdIn.nextInt() stdIn.nextInt stdIn boolean c=false; c false if(a-b>=k){
            c=true;
        }else{
            for(int i=a;i<=b;i++){
                if(i%k==0){
                   c=true; 
                }
            }
        } a-b>=k a-b a b k {
            c=true;
        } c=true c true {
            for(int i=a;i<=b;i++){
                if(i%k==0){
                   c=true; 
                }
            }
        } for(int i=a;i<=b;i++){
                if(i%k==0){
                   c=true; 
                }
            } int i=a; int i=a; i a i<=b i b i++ i++ i {
                if(i%k==0){
                   c=true; 
                }
            } {
                if(i%k==0){
                   c=true; 
                }
            } if(i%k==0){
                   c=true; 
                } i%k==0 i%k i k 0 {
                   c=true; 
                } c=true c true if(c){
            System.out.println("OK");
        }else{
            System.out.println("NG");
        } c {
            System.out.println("OK");
        } System.out.println("OK") System.out.println System.out System System.out "OK" {
            System.out.println("NG");
        } System.out.println("NG") System.out.println System.out System System.out "NG" String[] args args public class Main {
    public static void main(String[] args) throws Exception {
        Scanner stdIn= new Scanner(System.in);
        int k = stdIn.nextInt();
        int a = stdIn.nextInt();
        int b = stdIn.nextInt();
        boolean c=false;
        if(a-b>=k){
            c=true;
        }else{
            for(int i=a;i<=b;i++){
                if(i%k==0){
                   c=true; 
                }
            }
        }
        if(c){
            System.out.println("OK");
        }else{
            System.out.println("NG");
        }
    }
} public class Main {
    public static void main(String[] args) throws Exception {
        Scanner stdIn= new Scanner(System.in);
        int k = stdIn.nextInt();
        int a = stdIn.nextInt();
        int b = stdIn.nextInt();
        boolean c=false;
        if(a-b>=k){
            c=true;
        }else{
            for(int i=a;i<=b;i++){
                if(i%k==0){
                   c=true; 
                }
            }
        }
        if(c){
            System.out.println("OK");
        }else{
            System.out.println("NG");
        }
    }
} Main
import java.util.Scanner;
public class Main {
    public static void main(String[] args) throws Exception {
        Scanner stdIn= new Scanner(System.in);
        int k = stdIn.nextInt();
        int a = stdIn.nextInt();
        int b = stdIn.nextInt();
        boolean c=false;
        if(a-b>=k){
            c=true;
        }else{
            for(int i=a;i<=b;i++){
                if(i%k==0){
                   c=true; 
                }
            }
        }
        if(c){
            System.out.println("OK");
        }else{
            System.out.println("NG");
        }
    }
}