import java.util.Scanner;
public class Main
{
    public static void main(String Args[])
    {
        Scanner sc=new Scanner(System.in);
        int k=sc.nextInt();
        int a=sc.nextInt();
        int b=sc.nextInt();
        int n=a%k;
        int num=k-n;
        if(a+num<=b||n==0)
        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[])
    {
        Scanner sc=new Scanner(System.in);
        int k=sc.nextInt();
        int a=sc.nextInt();
        int b=sc.nextInt();
        int n=a%k;
        int num=k-n;
        if(a+num<=b||n==0)
        System.out.println("OK");
        else
        System.out.println("NG");
    }
    
} Main public static void main(String Args[])
    {
        Scanner sc=new Scanner(System.in);
        int k=sc.nextInt();
        int a=sc.nextInt();
        int b=sc.nextInt();
        int n=a%k;
        int num=k-n;
        if(a+num<=b||n==0)
        System.out.println("OK");
        else
        System.out.println("NG");
    } main {
        Scanner sc=new Scanner(System.in);
        int k=sc.nextInt();
        int a=sc.nextInt();
        int b=sc.nextInt();
        int n=a%k;
        int num=k-n;
        if(a+num<=b||n==0)
        System.out.println("OK");
        else
        System.out.println("NG");
    } Scanner sc=new Scanner(System.in); sc new Scanner(System.in) int k=sc.nextInt(); k sc.nextInt() sc.nextInt sc int a=sc.nextInt(); a sc.nextInt() sc.nextInt sc int b=sc.nextInt(); b sc.nextInt() sc.nextInt sc int n=a%k; n a%k a k int num=k-n; num k-n k n if(a+num<=b||n==0)
        System.out.println("OK");
        else
        System.out.println("NG"); a+num<=b||n==0 a+num<=b a+num a num b n==0 n 0 System.out.println("OK") System.out.println System.out System System.out "OK" 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[])
    {
        Scanner sc=new Scanner(System.in);
        int k=sc.nextInt();
        int a=sc.nextInt();
        int b=sc.nextInt();
        int n=a%k;
        int num=k-n;
        if(a+num<=b||n==0)
        System.out.println("OK");
        else
        System.out.println("NG");
    }
    
} public class Main
{
    public static void main(String Args[])
    {
        Scanner sc=new Scanner(System.in);
        int k=sc.nextInt();
        int a=sc.nextInt();
        int b=sc.nextInt();
        int n=a%k;
        int num=k-n;
        if(a+num<=b||n==0)
        System.out.println("OK");
        else
        System.out.println("NG");
    }
    
} Main
import java.util.Scanner;
public class Main
{
    public static void main(String Args[])
    {
        Scanner sc=new Scanner(System.in);
        int k=sc.nextInt();
        int a=sc.nextInt();
        int b=sc.nextInt();
        int n=a%k;
        int num=k-n;
        if(a+num<=b||n==0)
        System.out.println("OK");
        else
        System.out.println("NG");
    }
    
}
