import java.util.Scanner;

class Main{
  public static void main(String[]args){
    Scanner  sc=new Scanner(System.in);
    int k,a,b;
    k=sc.nextInt();
    a=sc.nextInt();
    b=sc.nextInt();
    boolean flag=true	;
    for(int i=a;i<=b;i++){
      if(i%k==0){
        System.out.println("OK");
       flag=false;
        break;
      }
    }
    if(flag)
      System.out.println("NG");
  }
} import java.util.Scanner; Scanner java.util class Main{
  public static void main(String[]args){
    Scanner  sc=new Scanner(System.in);
    int k,a,b;
    k=sc.nextInt();
    a=sc.nextInt();
    b=sc.nextInt();
    boolean flag=true	;
    for(int i=a;i<=b;i++){
      if(i%k==0){
        System.out.println("OK");
       flag=false;
        break;
      }
    }
    if(flag)
      System.out.println("NG");
  }
} Main public static void main(String[]args){
    Scanner  sc=new Scanner(System.in);
    int k,a,b;
    k=sc.nextInt();
    a=sc.nextInt();
    b=sc.nextInt();
    boolean flag=true	;
    for(int i=a;i<=b;i++){
      if(i%k==0){
        System.out.println("OK");
       flag=false;
        break;
      }
    }
    if(flag)
      System.out.println("NG");
  } main {
    Scanner  sc=new Scanner(System.in);
    int k,a,b;
    k=sc.nextInt();
    a=sc.nextInt();
    b=sc.nextInt();
    boolean flag=true	;
    for(int i=a;i<=b;i++){
      if(i%k==0){
        System.out.println("OK");
       flag=false;
        break;
      }
    }
    if(flag)
      System.out.println("NG");
  } Scanner  sc=new Scanner(System.in); sc new Scanner(System.in) int k k a a b; b k=sc.nextInt() k sc.nextInt() sc.nextInt sc a=sc.nextInt() a sc.nextInt() sc.nextInt sc b=sc.nextInt() b sc.nextInt() sc.nextInt sc boolean flag=true	; flag true for(int i=a;i<=b;i++){
      if(i%k==0){
        System.out.println("OK");
       flag=false;
        break;
      }
    } int i=a; int i=a; i a i<=b i b i++ i++ i {
      if(i%k==0){
        System.out.println("OK");
       flag=false;
        break;
      }
    } {
      if(i%k==0){
        System.out.println("OK");
       flag=false;
        break;
      }
    } if(i%k==0){
        System.out.println("OK");
       flag=false;
        break;
      } i%k==0 i%k i k 0 {
        System.out.println("OK");
       flag=false;
        break;
      } System.out.println("OK") System.out.println System.out System System.out "OK" flag=false flag false break; if(flag)
      System.out.println("NG"); flag System.out.println("NG") System.out.println System.out System System.out "NG" String[]args args
import java.util.Scanner;

class Main{
  public static void main(String[]args){
    Scanner  sc=new Scanner(System.in);
    int k,a,b;
    k=sc.nextInt();
    a=sc.nextInt();
    b=sc.nextInt();
    boolean flag=true	;
    for(int i=a;i<=b;i++){
      if(i%k==0){
        System.out.println("OK");
       flag=false;
        break;
      }
    }
    if(flag)
      System.out.println("NG");
  }
}
