import java.util.Scanner;
class Main{
public static void main(String[] args){
 Scanner scan = new Scanner(System.in);
 
 int K = scan.nextInt();
 int A = scan.nextInt();
 int B = scan.nextInt();
 int count = 0;
  
  for (int i = 0; i < B-A+1; i++){
  	if ((A + i) % K == 0){
      count += 1;
    }
    else{
    }
  }
  if (count > 0){
  System.out.println("OK");
  }
  if (count == 0){
    System.out.println("NG");
  }
 }
} import java.util.Scanner; Scanner java.util class Main{
public static void main(String[] args){
 Scanner scan = new Scanner(System.in);
 
 int K = scan.nextInt();
 int A = scan.nextInt();
 int B = scan.nextInt();
 int count = 0;
  
  for (int i = 0; i < B-A+1; i++){
  	if ((A + i) % K == 0){
      count += 1;
    }
    else{
    }
  }
  if (count > 0){
  System.out.println("OK");
  }
  if (count == 0){
    System.out.println("NG");
  }
 }
} Main public static void main(String[] args){
 Scanner scan = new Scanner(System.in);
 
 int K = scan.nextInt();
 int A = scan.nextInt();
 int B = scan.nextInt();
 int count = 0;
  
  for (int i = 0; i < B-A+1; i++){
  	if ((A + i) % K == 0){
      count += 1;
    }
    else{
    }
  }
  if (count > 0){
  System.out.println("OK");
  }
  if (count == 0){
    System.out.println("NG");
  }
 } main {
 Scanner scan = new Scanner(System.in);
 
 int K = scan.nextInt();
 int A = scan.nextInt();
 int B = scan.nextInt();
 int count = 0;
  
  for (int i = 0; i < B-A+1; i++){
  	if ((A + i) % K == 0){
      count += 1;
    }
    else{
    }
  }
  if (count > 0){
  System.out.println("OK");
  }
  if (count == 0){
    System.out.println("NG");
  }
 } Scanner scan = new Scanner(System.in); scan new Scanner(System.in) int K = scan.nextInt(); K scan.nextInt() scan.nextInt scan int A = scan.nextInt(); A scan.nextInt() scan.nextInt scan int B = scan.nextInt(); B scan.nextInt() scan.nextInt scan int count = 0; count 0 for (int i = 0; i < B-A+1; i++){
  	if ((A + i) % K == 0){
      count += 1;
    }
    else{
    }
  } int i = 0; int i = 0; i 0 i < B-A+1 i B-A+1 B-A B A 1 i++ i++ i {
  	if ((A + i) % K == 0){
      count += 1;
    }
    else{
    }
  } {
  	if ((A + i) % K == 0){
      count += 1;
    }
    else{
    }
  } if ((A + i) % K == 0){
      count += 1;
    }
    else{
    } (A + i) % K == 0 (A + i) % K (A + i) A i K 0 {
      count += 1;
    } count += 1 count 1 {
    } if (count > 0){
  System.out.println("OK");
  } count > 0 count 0 {
  System.out.println("OK");
  } System.out.println("OK") System.out.println System.out System System.out "OK" if (count == 0){
    System.out.println("NG");
  } count == 0 count 0 {
    System.out.println("NG");
  } 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 scan = new Scanner(System.in);
 
 int K = scan.nextInt();
 int A = scan.nextInt();
 int B = scan.nextInt();
 int count = 0;
  
  for (int i = 0; i < B-A+1; i++){
  	if ((A + i) % K == 0){
      count += 1;
    }
    else{
    }
  }
  if (count > 0){
  System.out.println("OK");
  }
  if (count == 0){
    System.out.println("NG");
  }
 }
}