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();
    String ans = "NG";
    for(int i = A; i<=B; i++){
            if(i%K == 0){
                ans = "OK";
            }
    }
    System.out.println(ans);
  }
} 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();
    String ans = "NG";
    for(int i = A; i<=B; i++){
            if(i%K == 0){
                ans = "OK";
            }
    }
    System.out.println(ans);
  }
} 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();
    String ans = "NG";
    for(int i = A; i<=B; i++){
            if(i%K == 0){
                ans = "OK";
            }
    }
    System.out.println(ans);
  } main {
    Scanner sc = new Scanner(System.in);
    int K = sc.nextInt();
    int A = sc.nextInt();
    int B = sc.nextInt();
    String ans = "NG";
    for(int i = A; i<=B; i++){
            if(i%K == 0){
                ans = "OK";
            }
    }
    System.out.println(ans);
  } 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 String ans = "NG"; ans "NG" for(int i = A; i<=B; i++){
            if(i%K == 0){
                ans = "OK";
            }
    } int i = A; int i = A; i A i<=B i B i++ i++ i {
            if(i%K == 0){
                ans = "OK";
            }
    } {
            if(i%K == 0){
                ans = "OK";
            }
    } if(i%K == 0){
                ans = "OK";
            } i%K == 0 i%K i K 0 {
                ans = "OK";
            } ans = "OK" ans "OK" System.out.println(ans) System.out.println System.out System System.out ans 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();
    String ans = "NG";
    for(int i = A; i<=B; i++){
            if(i%K == 0){
                ans = "OK";
            }
    }
    System.out.println(ans);
  }
} 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();
    String ans = "NG";
    for(int i = A; i<=B; i++){
            if(i%K == 0){
                ans = "OK";
            }
    }
    System.out.println(ans);
  }
} 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();
    String ans = "NG";
    for(int i = A; i<=B; i++){
            if(i%K == 0){
                ans = "OK";
            }
    }
    System.out.println(ans);
  }
}