import java.util.*;
import java.math.*;
     
class Main{
    public static void main(String[] args) {
        
        try(Scanner sc = new Scanner(System.in)){

            int k = Integer.parseInt(sc.next());
            int a = Integer.parseInt(sc.next());
            int b = Integer.parseInt(sc.next());

            boolean isNg = true;
            int i = 0;
            while(k <= b){
                k += i;
                if(i == 0) i = k;
                if(a <= k && k <= b){
                    System.out.println("OK");
                    isNg = false;
                    break;
                }
            }

            if(isNg) System.out.println("NG");

        }catch(Exception e){
            e.printStackTrace();
        }        
    }
} import java.util.*; util.* java import java.math.*; math.* java class Main{
    public static void main(String[] args) {
        
        try(Scanner sc = new Scanner(System.in)){

            int k = Integer.parseInt(sc.next());
            int a = Integer.parseInt(sc.next());
            int b = Integer.parseInt(sc.next());

            boolean isNg = true;
            int i = 0;
            while(k <= b){
                k += i;
                if(i == 0) i = k;
                if(a <= k && k <= b){
                    System.out.println("OK");
                    isNg = false;
                    break;
                }
            }

            if(isNg) System.out.println("NG");

        }catch(Exception e){
            e.printStackTrace();
        }        
    }
} Main public static void main(String[] args) {
        
        try(Scanner sc = new Scanner(System.in)){

            int k = Integer.parseInt(sc.next());
            int a = Integer.parseInt(sc.next());
            int b = Integer.parseInt(sc.next());

            boolean isNg = true;
            int i = 0;
            while(k <= b){
                k += i;
                if(i == 0) i = k;
                if(a <= k && k <= b){
                    System.out.println("OK");
                    isNg = false;
                    break;
                }
            }

            if(isNg) System.out.println("NG");

        }catch(Exception e){
            e.printStackTrace();
        }        
    } main {
        
        try(Scanner sc = new Scanner(System.in)){

            int k = Integer.parseInt(sc.next());
            int a = Integer.parseInt(sc.next());
            int b = Integer.parseInt(sc.next());

            boolean isNg = true;
            int i = 0;
            while(k <= b){
                k += i;
                if(i == 0) i = k;
                if(a <= k && k <= b){
                    System.out.println("OK");
                    isNg = false;
                    break;
                }
            }

            if(isNg) System.out.println("NG");

        }catch(Exception e){
            e.printStackTrace();
        }        
    } try(Scanner sc = new Scanner(System.in)){

            int k = Integer.parseInt(sc.next());
            int a = Integer.parseInt(sc.next());
            int b = Integer.parseInt(sc.next());

            boolean isNg = true;
            int i = 0;
            while(k <= b){
                k += i;
                if(i == 0) i = k;
                if(a <= k && k <= b){
                    System.out.println("OK");
                    isNg = false;
                    break;
                }
            }

            if(isNg) System.out.println("NG");

        }catch(Exception e){
            e.printStackTrace();
        } catch(Exception e){
            e.printStackTrace();
        } Exception e {
            e.printStackTrace();
        } e.printStackTrace() e.printStackTrace e {

            int k = Integer.parseInt(sc.next());
            int a = Integer.parseInt(sc.next());
            int b = Integer.parseInt(sc.next());

            boolean isNg = true;
            int i = 0;
            while(k <= b){
                k += i;
                if(i == 0) i = k;
                if(a <= k && k <= b){
                    System.out.println("OK");
                    isNg = false;
                    break;
                }
            }

            if(isNg) System.out.println("NG");

        } Scanner sc = new Scanner(System.in) Scanner sc = new Scanner(System.in) new Scanner(System.in) int k = Integer.parseInt(sc.next()); k Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc int a = Integer.parseInt(sc.next()); a Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc int b = Integer.parseInt(sc.next()); b Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc boolean isNg = true; isNg true int i = 0; i 0 while(k <= b){
                k += i;
                if(i == 0) i = k;
                if(a <= k && k <= b){
                    System.out.println("OK");
                    isNg = false;
                    break;
                }
            } k <= b k b {
                k += i;
                if(i == 0) i = k;
                if(a <= k && k <= b){
                    System.out.println("OK");
                    isNg = false;
                    break;
                }
            } k += i k i if(i == 0) i = k; i == 0 i 0 i = k i k if(a <= k && k <= b){
                    System.out.println("OK");
                    isNg = false;
                    break;
                } a <= k && k <= b a <= k a k k <= b k b {
                    System.out.println("OK");
                    isNg = false;
                    break;
                } System.out.println("OK") System.out.println System.out System System.out "OK" isNg = false isNg false break; if(isNg) System.out.println("NG"); isNg System.out.println("NG") System.out.println System.out System System.out "NG" String[] args args
import java.util.*;
import java.math.*;
     
class Main{
    public static void main(String[] args) {
        
        try(Scanner sc = new Scanner(System.in)){

            int k = Integer.parseInt(sc.next());
            int a = Integer.parseInt(sc.next());
            int b = Integer.parseInt(sc.next());

            boolean isNg = true;
            int i = 0;
            while(k <= b){
                k += i;
                if(i == 0) i = k;
                if(a <= k && k <= b){
                    System.out.println("OK");
                    isNg = false;
                    break;
                }
            }

            if(isNg) System.out.println("NG");

        }catch(Exception e){
            e.printStackTrace();
        }        
    }
}
