import java.util.*;
import java.io.*;

public class Main {

    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner in = new Scanner(new BufferedReader(new InputStreamReader(System.in)));
        
        
        int K = in.nextInt();
        in.nextLine();
        int A = in.nextInt();
        int B = in.nextInt();
        

        boolean isDone = false;
        
        for(int i = A; i <= B; i++) {
            if(i%K == 0) {
                isDone = true;
                System.out.println("OK");
                break;
            }
        }
        
        if(!isDone) System.out.println("NG");
    }
    

        
} import java.util.*; util.* java import java.io.*; io.* java public class Main {

    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner in = new Scanner(new BufferedReader(new InputStreamReader(System.in)));
        
        
        int K = in.nextInt();
        in.nextLine();
        int A = in.nextInt();
        int B = in.nextInt();
        

        boolean isDone = false;
        
        for(int i = A; i <= B; i++) {
            if(i%K == 0) {
                isDone = true;
                System.out.println("OK");
                break;
            }
        }
        
        if(!isDone) System.out.println("NG");
    }
    

        
} Main public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner in = new Scanner(new BufferedReader(new InputStreamReader(System.in)));
        
        
        int K = in.nextInt();
        in.nextLine();
        int A = in.nextInt();
        int B = in.nextInt();
        

        boolean isDone = false;
        
        for(int i = A; i <= B; i++) {
            if(i%K == 0) {
                isDone = true;
                System.out.println("OK");
                break;
            }
        }
        
        if(!isDone) System.out.println("NG");
    } main {
        // Your code here!
        Scanner in = new Scanner(new BufferedReader(new InputStreamReader(System.in)));
        
        
        int K = in.nextInt();
        in.nextLine();
        int A = in.nextInt();
        int B = in.nextInt();
        

        boolean isDone = false;
        
        for(int i = A; i <= B; i++) {
            if(i%K == 0) {
                isDone = true;
                System.out.println("OK");
                break;
            }
        }
        
        if(!isDone) System.out.println("NG");
    } Scanner in = new Scanner(new BufferedReader(new InputStreamReader(System.in))); in new Scanner(new BufferedReader(new InputStreamReader(System.in))) int K = in.nextInt(); K in.nextInt() in.nextInt in in.nextLine() in.nextLine in int A = in.nextInt(); A in.nextInt() in.nextInt in int B = in.nextInt(); B in.nextInt() in.nextInt in boolean isDone = false; isDone false for(int i = A; i <= B; i++) {
            if(i%K == 0) {
                isDone = true;
                System.out.println("OK");
                break;
            }
        } int i = A; int i = A; i A i <= B i B i++ i++ i {
            if(i%K == 0) {
                isDone = true;
                System.out.println("OK");
                break;
            }
        } {
            if(i%K == 0) {
                isDone = true;
                System.out.println("OK");
                break;
            }
        } if(i%K == 0) {
                isDone = true;
                System.out.println("OK");
                break;
            } i%K == 0 i%K i K 0 {
                isDone = true;
                System.out.println("OK");
                break;
            } isDone = true isDone true System.out.println("OK") System.out.println System.out System System.out "OK" break; if(!isDone) System.out.println("NG"); !isDone isDone 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) throws Exception {
        // Your code here!
        Scanner in = new Scanner(new BufferedReader(new InputStreamReader(System.in)));
        
        
        int K = in.nextInt();
        in.nextLine();
        int A = in.nextInt();
        int B = in.nextInt();
        

        boolean isDone = false;
        
        for(int i = A; i <= B; i++) {
            if(i%K == 0) {
                isDone = true;
                System.out.println("OK");
                break;
            }
        }
        
        if(!isDone) System.out.println("NG");
    }
    

        
} public class Main {

    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner in = new Scanner(new BufferedReader(new InputStreamReader(System.in)));
        
        
        int K = in.nextInt();
        in.nextLine();
        int A = in.nextInt();
        int B = in.nextInt();
        

        boolean isDone = false;
        
        for(int i = A; i <= B; i++) {
            if(i%K == 0) {
                isDone = true;
                System.out.println("OK");
                break;
            }
        }
        
        if(!isDone) System.out.println("NG");
    }
    

        
} Main
import java.util.*;
import java.io.*;

public class Main {

    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner in = new Scanner(new BufferedReader(new InputStreamReader(System.in)));
        
        
        int K = in.nextInt();
        in.nextLine();
        int A = in.nextInt();
        int B = in.nextInt();
        

        boolean isDone = false;
        
        for(int i = A; i <= B; i++) {
            if(i%K == 0) {
                isDone = true;
                System.out.println("OK");
                break;
            }
        }
        
        if(!isDone) System.out.println("NG");
    }
    

        
}
