import java.util.Scanner;
 
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();
 
        if(a%k==0||b%k==0)
        {
            System.out.print("OK");
        }
        else
        if((b/k)-(a)/k>=1)
        {
            System.out.print("OK");
        }
        else
        {
            System.out.print("NG");
        }
    }
} import java.util.Scanner; Scanner java.util 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();
 
        if(a%k==0||b%k==0)
        {
            System.out.print("OK");
        }
        else
        if((b/k)-(a)/k>=1)
        {
            System.out.print("OK");
        }
        else
        {
            System.out.print("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();
 
        if(a%k==0||b%k==0)
        {
            System.out.print("OK");
        }
        else
        if((b/k)-(a)/k>=1)
        {
            System.out.print("OK");
        }
        else
        {
            System.out.print("NG");
        }
    } main {
        Scanner sc = new Scanner(System.in);
        int k =sc.nextInt();
        int a = sc.nextInt();
        int b = sc.nextInt();
 
        if(a%k==0||b%k==0)
        {
            System.out.print("OK");
        }
        else
        if((b/k)-(a)/k>=1)
        {
            System.out.print("OK");
        }
        else
        {
            System.out.print("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 if(a%k==0||b%k==0)
        {
            System.out.print("OK");
        }
        else
        if((b/k)-(a)/k>=1)
        {
            System.out.print("OK");
        }
        else
        {
            System.out.print("NG");
        } a%k==0||b%k==0 a%k==0 a%k a k 0 b%k==0 b%k b k 0 {
            System.out.print("OK");
        } System.out.print("OK") System.out.print System.out System System.out "OK" if((b/k)-(a)/k>=1)
        {
            System.out.print("OK");
        }
        else
        {
            System.out.print("NG");
        } (b/k)-(a)/k>=1 (b/k)-(a)/k (b/k) b k (a)/k (a) k 1 {
            System.out.print("OK");
        } System.out.print("OK") System.out.print System.out System System.out "OK" {
            System.out.print("NG");
        } System.out.print("NG") System.out.print System.out System System.out "NG" String args[] args
import java.util.Scanner;
 
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();
 
        if(a%k==0||b%k==0)
        {
            System.out.print("OK");
        }
        else
        if((b/k)-(a)/k>=1)
        {
            System.out.print("OK");
        }
        else
        {
            System.out.print("NG");
        }
    }
}