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 flag=0;
    for( int i=a;i<=b;i++){
      if(i%k==0){
        flag++;
      }
    }
    if(flag>0){
      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 flag=0;
    for( int i=a;i<=b;i++){
      if(i%k==0){
        flag++;
      }
    }
    if(flag>0){
      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 flag=0;
    for( int i=a;i<=b;i++){
      if(i%k==0){
        flag++;
      }
    }
    if(flag>0){
      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 flag=0;
    for( int i=a;i<=b;i++){
      if(i%k==0){
        flag++;
      }
    }
    if(flag>0){
      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 flag=0; flag 0 for( int i=a;i<=b;i++){
      if(i%k==0){
        flag++;
      }
    } int i=a; int i=a; i a i<=b i b i++ i++ i {
      if(i%k==0){
        flag++;
      }
    } {
      if(i%k==0){
        flag++;
      }
    } if(i%k==0){
        flag++;
      } i%k==0 i%k i k 0 {
        flag++;
      } flag++ flag if(flag>0){
      System.out.println("OK");
    }else{
      System.out.println("NG");
    } flag>0 flag 0 {
      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 flag=0;
    for( int i=a;i<=b;i++){
      if(i%k==0){
        flag++;
      }
    }
    if(flag>0){
      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 flag=0;
    for( int i=a;i<=b;i++){
      if(i%k==0){
        flag++;
      }
    }
    if(flag>0){
      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 flag=0;
    for( int i=a;i<=b;i++){
      if(i%k==0){
        flag++;
      }
    }
    if(flag>0){
      System.out.println("OK");
    }else{
      System.out.println("NG");
    }
   }
}