
import 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 ad = 0;
        int ans = 0;
        sc.close();

        ad = a;
        for(int i=0 ; i<=(b-ad) ; i++){
            ans = (a%k==0)?1:0;
            if(ans == 1){break;}
            a++;
        }
        if(ans == 1){
            System.out.println("OK");
        }else{      
            System.out.println("NG");
        }
    }
} import java.util.*; util.* java 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 ad = 0;
        int ans = 0;
        sc.close();

        ad = a;
        for(int i=0 ; i<=(b-ad) ; i++){
            ans = (a%k==0)?1:0;
            if(ans == 1){break;}
            a++;
        }
        if(ans == 1){
            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 ad = 0;
        int ans = 0;
        sc.close();

        ad = a;
        for(int i=0 ; i<=(b-ad) ; i++){
            ans = (a%k==0)?1:0;
            if(ans == 1){break;}
            a++;
        }
        if(ans == 1){
            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 ad = 0;
        int ans = 0;
        sc.close();

        ad = a;
        for(int i=0 ; i<=(b-ad) ; i++){
            ans = (a%k==0)?1:0;
            if(ans == 1){break;}
            a++;
        }
        if(ans == 1){
            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 ad = 0; ad 0 int ans = 0; ans 0 sc.close() sc.close sc ad = a ad a for(int i=0 ; i<=(b-ad) ; i++){
            ans = (a%k==0)?1:0;
            if(ans == 1){break;}
            a++;
        } int i=0 ; int i=0 ; i 0 i<=(b-ad) i (b-ad) b ad i++ i++ i {
            ans = (a%k==0)?1:0;
            if(ans == 1){break;}
            a++;
        } {
            ans = (a%k==0)?1:0;
            if(ans == 1){break;}
            a++;
        } ans = (a%k==0)?1:0 ans (a%k==0)?1:0 (a%k==0) a%k a k 0 1 0 if(ans == 1){break;} ans == 1 ans 1 {break;} break; a++ a if(ans == 1){
            System.out.println("OK");
        }else{      
            System.out.println("NG");
        } ans == 1 ans 1 {
            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 sc = new Scanner(System.in);

        int k = sc.nextInt();
        int a = sc.nextInt();
        int b = sc.nextInt();
        int ad = 0;
        int ans = 0;
        sc.close();

        ad = a;
        for(int i=0 ; i<=(b-ad) ; i++){
            ans = (a%k==0)?1:0;
            if(ans == 1){break;}
            a++;
        }
        if(ans == 1){
            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 ad = 0;
        int ans = 0;
        sc.close();

        ad = a;
        for(int i=0 ; i<=(b-ad) ; i++){
            ans = (a%k==0)?1:0;
            if(ans == 1){break;}
            a++;
        }
        if(ans == 1){
            System.out.println("OK");
        }else{      
            System.out.println("NG");
        }
    }
} Main

import 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 ad = 0;
        int ans = 0;
        sc.close();

        ad = a;
        for(int i=0 ; i<=(b-ad) ; i++){
            ans = (a%k==0)?1:0;
            if(ans == 1){break;}
            a++;
        }
        if(ans == 1){
            System.out.println("OK");
        }else{      
            System.out.println("NG");
        }
    }
}