import java.util.Scanner;
public class Main {

    public static void main(String[] args) {
        Scanner scan=new Scanner(System.in);
int K= scan.nextInt();

        int A= scan.nextInt();

        int B= scan.nextInt();

        int N=A%K;
        if((N+B-A>=K)||(N==0)){System.out.println("OK");}
        else {System.out.println("NG");};



        // write your code here
    }
} import java.util.Scanner; Scanner java.util public class Main {

    public static void main(String[] args) {
        Scanner scan=new Scanner(System.in);
int K= scan.nextInt();

        int A= scan.nextInt();

        int B= scan.nextInt();

        int N=A%K;
        if((N+B-A>=K)||(N==0)){System.out.println("OK");}
        else {System.out.println("NG");};



        // write your code here
    }
} Main public static void main(String[] args) {
        Scanner scan=new Scanner(System.in);
int K= scan.nextInt();

        int A= scan.nextInt();

        int B= scan.nextInt();

        int N=A%K;
        if((N+B-A>=K)||(N==0)){System.out.println("OK");}
        else {System.out.println("NG");};



        // write your code here
    } main {
        Scanner scan=new Scanner(System.in);
int K= scan.nextInt();

        int A= scan.nextInt();

        int B= scan.nextInt();

        int N=A%K;
        if((N+B-A>=K)||(N==0)){System.out.println("OK");}
        else {System.out.println("NG");};



        // write your code here
    } Scanner scan=new Scanner(System.in); scan new Scanner(System.in) int K= scan.nextInt(); K scan.nextInt() scan.nextInt scan int A= scan.nextInt(); A scan.nextInt() scan.nextInt scan int B= scan.nextInt(); B scan.nextInt() scan.nextInt scan int N=A%K; N A%K A K if((N+B-A>=K)||(N==0)){System.out.println("OK");}
        else {System.out.println("NG");} (N+B-A>=K)||(N==0) (N+B-A>=K) N+B-A N+B N B A K (N==0) N 0 {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) {
        Scanner scan=new Scanner(System.in);
int K= scan.nextInt();

        int A= scan.nextInt();

        int B= scan.nextInt();

        int N=A%K;
        if((N+B-A>=K)||(N==0)){System.out.println("OK");}
        else {System.out.println("NG");};



        // write your code here
    }
} public class Main {

    public static void main(String[] args) {
        Scanner scan=new Scanner(System.in);
int K= scan.nextInt();

        int A= scan.nextInt();

        int B= scan.nextInt();

        int N=A%K;
        if((N+B-A>=K)||(N==0)){System.out.println("OK");}
        else {System.out.println("NG");};



        // write your code here
    }
} Main
import java.util.Scanner;
public class Main {

    public static void main(String[] args) {
        Scanner scan=new Scanner(System.in);
int K= scan.nextInt();

        int A= scan.nextInt();

        int B= scan.nextInt();

        int N=A%K;
        if((N+B-A>=K)||(N==0)){System.out.println("OK");}
        else {System.out.println("NG");};



        // write your code here
    }
}