import java.util.*;
public class Main{
  public static void main(String[] args){
    Scanner scanner = new Scanner(System.in);
    
    int k = scanner.nextInt();
    int a = scanner.nextInt();
    int b = scanner.nextInt();
 
    int mulValue = k;
    
    for(int mulCount = 1; mulValue <= b; mulCount++){
      mulValue = k * mulCount;
      if(a <= mulValue && mulValue <= 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 scanner = new Scanner(System.in);
    
    int k = scanner.nextInt();
    int a = scanner.nextInt();
    int b = scanner.nextInt();
 
    int mulValue = k;
    
    for(int mulCount = 1; mulValue <= b; mulCount++){
      mulValue = k * mulCount;
      if(a <= mulValue && mulValue <= b){
        System.out.println("OK");
        return;
      }
    }
    System.out.println("NG");
  }
} Main public static void main(String[] args){
    Scanner scanner = new Scanner(System.in);
    
    int k = scanner.nextInt();
    int a = scanner.nextInt();
    int b = scanner.nextInt();
 
    int mulValue = k;
    
    for(int mulCount = 1; mulValue <= b; mulCount++){
      mulValue = k * mulCount;
      if(a <= mulValue && mulValue <= b){
        System.out.println("OK");
        return;
      }
    }
    System.out.println("NG");
  } main {
    Scanner scanner = new Scanner(System.in);
    
    int k = scanner.nextInt();
    int a = scanner.nextInt();
    int b = scanner.nextInt();
 
    int mulValue = k;
    
    for(int mulCount = 1; mulValue <= b; mulCount++){
      mulValue = k * mulCount;
      if(a <= mulValue && mulValue <= b){
        System.out.println("OK");
        return;
      }
    }
    System.out.println("NG");
  } Scanner scanner = new Scanner(System.in); scanner new Scanner(System.in) int k = scanner.nextInt(); k scanner.nextInt() scanner.nextInt scanner int a = scanner.nextInt(); a scanner.nextInt() scanner.nextInt scanner int b = scanner.nextInt(); b scanner.nextInt() scanner.nextInt scanner int mulValue = k; mulValue k for(int mulCount = 1; mulValue <= b; mulCount++){
      mulValue = k * mulCount;
      if(a <= mulValue && mulValue <= b){
        System.out.println("OK");
        return;
      }
    } int mulCount = 1; int mulCount = 1; mulCount 1 mulValue <= b mulValue b mulCount++ mulCount++ mulCount {
      mulValue = k * mulCount;
      if(a <= mulValue && mulValue <= b){
        System.out.println("OK");
        return;
      }
    } {
      mulValue = k * mulCount;
      if(a <= mulValue && mulValue <= b){
        System.out.println("OK");
        return;
      }
    } mulValue = k * mulCount mulValue k * mulCount k mulCount if(a <= mulValue && mulValue <= b){
        System.out.println("OK");
        return;
      } a <= mulValue && mulValue <= b a <= mulValue a mulValue mulValue <= b mulValue 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 scanner = new Scanner(System.in);
    
    int k = scanner.nextInt();
    int a = scanner.nextInt();
    int b = scanner.nextInt();
 
    int mulValue = k;
    
    for(int mulCount = 1; mulValue <= b; mulCount++){
      mulValue = k * mulCount;
      if(a <= mulValue && mulValue <= b){
        System.out.println("OK");
        return;
      }
    }
    System.out.println("NG");
  }
} public class Main{
  public static void main(String[] args){
    Scanner scanner = new Scanner(System.in);
    
    int k = scanner.nextInt();
    int a = scanner.nextInt();
    int b = scanner.nextInt();
 
    int mulValue = k;
    
    for(int mulCount = 1; mulValue <= b; mulCount++){
      mulValue = k * mulCount;
      if(a <= mulValue && mulValue <= b){
        System.out.println("OK");
        return;
      }
    }
    System.out.println("NG");
  }
} Main
import java.util.*;
public class Main{
  public static void main(String[] args){
    Scanner scanner = new Scanner(System.in);
    
    int k = scanner.nextInt();
    int a = scanner.nextInt();
    int b = scanner.nextInt();
 
    int mulValue = k;
    
    for(int mulCount = 1; mulValue <= b; mulCount++){
      mulValue = k * mulCount;
      if(a <= mulValue && mulValue <= b){
        System.out.println("OK");
        return;
      }
    }
    System.out.println("NG");
  }
}