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();
    for(int i = 1;i<1001;i++){
      int tmp = k * i;
      if(a <= tmp && tmp <= b){
        System.out.println("OK");
        return;
      }
    }
    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();
    for(int i = 1;i<1001;i++){
      int tmp = k * i;
      if(a <= tmp && tmp <= b){
        System.out.println("OK");
        return;
      }
    }
    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();
    for(int i = 1;i<1001;i++){
      int tmp = k * i;
      if(a <= tmp && tmp <= b){
        System.out.println("OK");
        return;
      }
    }
    System.out.println("NG");
  } main {
    Scanner sc = new Scanner(System.in);
    int k = sc.nextInt();
    int a = sc.nextInt();
    int b = sc.nextInt();
    for(int i = 1;i<1001;i++){
      int tmp = k * i;
      if(a <= tmp && tmp <= b){
        System.out.println("OK");
        return;
      }
    }
    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 for(int i = 1;i<1001;i++){
      int tmp = k * i;
      if(a <= tmp && tmp <= b){
        System.out.println("OK");
        return;
      }
    } int i = 1; int i = 1; i 1 i<1001 i 1001 i++ i++ i {
      int tmp = k * i;
      if(a <= tmp && tmp <= b){
        System.out.println("OK");
        return;
      }
    } {
      int tmp = k * i;
      if(a <= tmp && tmp <= b){
        System.out.println("OK");
        return;
      }
    } int tmp = k * i; tmp k * i k i if(a <= tmp && tmp <= b){
        System.out.println("OK");
        return;
      } a <= tmp && tmp <= b a <= tmp a tmp tmp <= b tmp b {
        System.out.println("OK");
        return;
      } System.out.println("OK") System.out.println System.out System System.out "OK" return; 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();
    for(int i = 1;i<1001;i++){
      int tmp = k * i;
      if(a <= tmp && tmp <= b){
        System.out.println("OK");
        return;
      }
    }
    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();
    for(int i = 1;i<1001;i++){
      int tmp = k * i;
      if(a <= tmp && tmp <= b){
        System.out.println("OK");
        return;
      }
    }
    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();
    for(int i = 1;i<1001;i++){
      int tmp = k * i;
      if(a <= tmp && tmp <= b){
        System.out.println("OK");
        return;
      }
    }
    System.out.println("NG");
  }
}
