import java.util.*;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		// 整数の入力(スペース改行関係なし)
		int k = sc.nextInt();
		int a = sc.nextInt();
      	int b = sc.nextInt();
		int i = 0;
        boolean iketaka = false;
      	for(i = a ; i <= b ; i++){
        	if(i%k == 0){
            	System.out.println("OK");
              	iketaka = true;
              	break;
            }
        	i += 1;
        }
		if(!iketaka){
          System.out.println("NG");
        }
		
	}
} import java.util.*; util.* java public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		// 整数の入力(スペース改行関係なし)
		int k = sc.nextInt();
		int a = sc.nextInt();
      	int b = sc.nextInt();
		int i = 0;
        boolean iketaka = false;
      	for(i = a ; i <= b ; i++){
        	if(i%k == 0){
            	System.out.println("OK");
              	iketaka = true;
              	break;
            }
        	i += 1;
        }
		if(!iketaka){
          System.out.println("NG");
        }
		
	}
} Main public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		// 整数の入力(スペース改行関係なし)
		int k = sc.nextInt();
		int a = sc.nextInt();
      	int b = sc.nextInt();
		int i = 0;
        boolean iketaka = false;
      	for(i = a ; i <= b ; i++){
        	if(i%k == 0){
            	System.out.println("OK");
              	iketaka = true;
              	break;
            }
        	i += 1;
        }
		if(!iketaka){
          System.out.println("NG");
        }
		
	} main {
		Scanner sc = new Scanner(System.in);
		// 整数の入力(スペース改行関係なし)
		int k = sc.nextInt();
		int a = sc.nextInt();
      	int b = sc.nextInt();
		int i = 0;
        boolean iketaka = false;
      	for(i = a ; i <= b ; i++){
        	if(i%k == 0){
            	System.out.println("OK");
              	iketaka = true;
              	break;
            }
        	i += 1;
        }
		if(!iketaka){
          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 i = 0; i 0 boolean iketaka = false; iketaka false for(i = a ; i <= b ; i++){
        	if(i%k == 0){
            	System.out.println("OK");
              	iketaka = true;
              	break;
            }
        	i += 1;
        } i = a ; i = a i a i <= b i b i++ i++ i {
        	if(i%k == 0){
            	System.out.println("OK");
              	iketaka = true;
              	break;
            }
        	i += 1;
        } {
        	if(i%k == 0){
            	System.out.println("OK");
              	iketaka = true;
              	break;
            }
        	i += 1;
        } if(i%k == 0){
            	System.out.println("OK");
              	iketaka = true;
              	break;
            } i%k == 0 i%k i k 0 {
            	System.out.println("OK");
              	iketaka = true;
              	break;
            } System.out.println("OK") System.out.println System.out System System.out "OK" iketaka = true iketaka true break; i += 1 i 1 if(!iketaka){
          System.out.println("NG");
        } !iketaka iketaka {
          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);
		// 整数の入力(スペース改行関係なし)
		int k = sc.nextInt();
		int a = sc.nextInt();
      	int b = sc.nextInt();
		int i = 0;
        boolean iketaka = false;
      	for(i = a ; i <= b ; i++){
        	if(i%k == 0){
            	System.out.println("OK");
              	iketaka = true;
              	break;
            }
        	i += 1;
        }
		if(!iketaka){
          System.out.println("NG");
        }
		
	}
} public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		// 整数の入力(スペース改行関係なし)
		int k = sc.nextInt();
		int a = sc.nextInt();
      	int b = sc.nextInt();
		int i = 0;
        boolean iketaka = false;
      	for(i = a ; i <= b ; i++){
        	if(i%k == 0){
            	System.out.println("OK");
              	iketaka = true;
              	break;
            }
        	i += 1;
        }
		if(!iketaka){
          System.out.println("NG");
        }
		
	}
} Main
import java.util.*;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		// 整数の入力(スペース改行関係なし)
		int k = sc.nextInt();
		int a = sc.nextInt();
      	int b = sc.nextInt();
		int i = 0;
        boolean iketaka = false;
      	for(i = a ; i <= b ; i++){
        	if(i%k == 0){
            	System.out.println("OK");
              	iketaka = true;
              	break;
            }
        	i += 1;
        }
		if(!iketaka){
          System.out.println("NG");
        }
		
	}
}