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 count = k;
        boolean bool = false;
        while (count<=b){
            if (a<=count&&count<=b)bool=true;
            count+=k;
        }
        if (bool)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 count = k;
        boolean bool = false;
        while (count<=b){
            if (a<=count&&count<=b)bool=true;
            count+=k;
        }
        if (bool)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 count = k;
        boolean bool = false;
        while (count<=b){
            if (a<=count&&count<=b)bool=true;
            count+=k;
        }
        if (bool)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 count = k;
        boolean bool = false;
        while (count<=b){
            if (a<=count&&count<=b)bool=true;
            count+=k;
        }
        if (bool)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 count = k; count k boolean bool = false; bool false while (count<=b){
            if (a<=count&&count<=b)bool=true;
            count+=k;
        } count<=b count b {
            if (a<=count&&count<=b)bool=true;
            count+=k;
        } if (a<=count&&count<=b)bool=true; a<=count&&count<=b a<=count a count count<=b count b bool=true bool true count+=k count k if (bool)System.out.println("OK");
        else System.out.println("NG"); bool 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 count = k;
        boolean bool = false;
        while (count<=b){
            if (a<=count&&count<=b)bool=true;
            count+=k;
        }
        if (bool)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 count = k;
        boolean bool = false;
        while (count<=b){
            if (a<=count&&count<=b)bool=true;
            count+=k;
        }
        if (bool)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 count = k;
        boolean bool = false;
        while (count<=b){
            if (a<=count&&count<=b)bool=true;
            count+=k;
        }
        if (bool)System.out.println("OK");
        else System.out.println("NG");
    }
}
