import java.util.*; 
public class Main
{
    public static void main(String args[])
    {
        Scanner in=new Scanner(System.in);
        int k;
        k=in.nextInt();
        int a,b,i,num;
        a=in.nextInt();
        b=in.nextInt();
        num=a;
        for(i=num;i<=b;i++,num++)
        {
            if(i%k==0)
            {
                System.out.println("OK");
                System.exit(0);
            }
        }
        System.out.println("NG");
    }
} import java.util.*; util.* java public class Main
{
    public static void main(String args[])
    {
        Scanner in=new Scanner(System.in);
        int k;
        k=in.nextInt();
        int a,b,i,num;
        a=in.nextInt();
        b=in.nextInt();
        num=a;
        for(i=num;i<=b;i++,num++)
        {
            if(i%k==0)
            {
                System.out.println("OK");
                System.exit(0);
            }
        }
        System.out.println("NG");
    }
} Main public static void main(String args[])
    {
        Scanner in=new Scanner(System.in);
        int k;
        k=in.nextInt();
        int a,b,i,num;
        a=in.nextInt();
        b=in.nextInt();
        num=a;
        for(i=num;i<=b;i++,num++)
        {
            if(i%k==0)
            {
                System.out.println("OK");
                System.exit(0);
            }
        }
        System.out.println("NG");
    } main {
        Scanner in=new Scanner(System.in);
        int k;
        k=in.nextInt();
        int a,b,i,num;
        a=in.nextInt();
        b=in.nextInt();
        num=a;
        for(i=num;i<=b;i++,num++)
        {
            if(i%k==0)
            {
                System.out.println("OK");
                System.exit(0);
            }
        }
        System.out.println("NG");
    } Scanner in=new Scanner(System.in); in new Scanner(System.in) int k; k k=in.nextInt() k in.nextInt() in.nextInt in int a a b b i i num; num a=in.nextInt() a in.nextInt() in.nextInt in b=in.nextInt() b in.nextInt() in.nextInt in num=a num a for(i=num;i<=b;i++,num++)
        {
            if(i%k==0)
            {
                System.out.println("OK");
                System.exit(0);
            }
        } i=num; i=num i num i<=b i b i++,num++ i++ i num++ num {
            if(i%k==0)
            {
                System.out.println("OK");
                System.exit(0);
            }
        } {
            if(i%k==0)
            {
                System.out.println("OK");
                System.exit(0);
            }
        } if(i%k==0)
            {
                System.out.println("OK");
                System.exit(0);
            } i%k==0 i%k i k 0 {
                System.out.println("OK");
                System.exit(0);
            } System.out.println("OK") System.out.println System.out System System.out "OK" System.exit(0) System.exit System 0 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 in=new Scanner(System.in);
        int k;
        k=in.nextInt();
        int a,b,i,num;
        a=in.nextInt();
        b=in.nextInt();
        num=a;
        for(i=num;i<=b;i++,num++)
        {
            if(i%k==0)
            {
                System.out.println("OK");
                System.exit(0);
            }
        }
        System.out.println("NG");
    }
} public class Main
{
    public static void main(String args[])
    {
        Scanner in=new Scanner(System.in);
        int k;
        k=in.nextInt();
        int a,b,i,num;
        a=in.nextInt();
        b=in.nextInt();
        num=a;
        for(i=num;i<=b;i++,num++)
        {
            if(i%k==0)
            {
                System.out.println("OK");
                System.exit(0);
            }
        }
        System.out.println("NG");
    }
} Main
import java.util.*; 
public class Main
{
    public static void main(String args[])
    {
        Scanner in=new Scanner(System.in);
        int k;
        k=in.nextInt();
        int a,b,i,num;
        a=in.nextInt();
        b=in.nextInt();
        num=a;
        for(i=num;i<=b;i++,num++)
        {
            if(i%k==0)
            {
                System.out.println("OK");
                System.exit(0);
            }
        }
        System.out.println("NG");
    }
}