
import java.util.Scanner;
import java.util.Arrays;
import java.util.stream.*;

public class Main {
    public static void main(String[] args) {
        //コード
        Scanner scanner = new Scanner(System.in);
        Integer k = Integer.parseInt(scanner.next());
        Integer a = Integer.parseInt(scanner.next());
        Integer b = Integer.parseInt(scanner.next());


        int total = 0;
        for(int i = 1; i <= b; i++) {
            total = k * i;
            if(total >= a && total <= b) {
                System.out.println("OK");
                break;
            }
            if(total >= b) {
                System.out.println("NG");
                break;
            }
        }
    }
} import java.util.Scanner; Scanner java.util import java.util.Arrays; Arrays java.util import java.util.stream.*; stream.* java.util public class Main {
    public static void main(String[] args) {
        //コード
        Scanner scanner = new Scanner(System.in);
        Integer k = Integer.parseInt(scanner.next());
        Integer a = Integer.parseInt(scanner.next());
        Integer b = Integer.parseInt(scanner.next());


        int total = 0;
        for(int i = 1; i <= b; i++) {
            total = k * i;
            if(total >= a && total <= b) {
                System.out.println("OK");
                break;
            }
            if(total >= b) {
                System.out.println("NG");
                break;
            }
        }
    }
} Main public static void main(String[] args) {
        //コード
        Scanner scanner = new Scanner(System.in);
        Integer k = Integer.parseInt(scanner.next());
        Integer a = Integer.parseInt(scanner.next());
        Integer b = Integer.parseInt(scanner.next());


        int total = 0;
        for(int i = 1; i <= b; i++) {
            total = k * i;
            if(total >= a && total <= b) {
                System.out.println("OK");
                break;
            }
            if(total >= b) {
                System.out.println("NG");
                break;
            }
        }
    } main {
        //コード
        Scanner scanner = new Scanner(System.in);
        Integer k = Integer.parseInt(scanner.next());
        Integer a = Integer.parseInt(scanner.next());
        Integer b = Integer.parseInt(scanner.next());


        int total = 0;
        for(int i = 1; i <= b; i++) {
            total = k * i;
            if(total >= a && total <= b) {
                System.out.println("OK");
                break;
            }
            if(total >= b) {
                System.out.println("NG");
                break;
            }
        }
    } Scanner scanner = new Scanner(System.in); scanner new Scanner(System.in) Integer k = Integer.parseInt(scanner.next()); k Integer.parseInt(scanner.next()) Integer.parseInt Integer scanner.next() scanner.next scanner Integer a = Integer.parseInt(scanner.next()); a Integer.parseInt(scanner.next()) Integer.parseInt Integer scanner.next() scanner.next scanner Integer b = Integer.parseInt(scanner.next()); b Integer.parseInt(scanner.next()) Integer.parseInt Integer scanner.next() scanner.next scanner int total = 0; total 0 for(int i = 1; i <= b; i++) {
            total = k * i;
            if(total >= a && total <= b) {
                System.out.println("OK");
                break;
            }
            if(total >= b) {
                System.out.println("NG");
                break;
            }
        } int i = 1; int i = 1; i 1 i <= b i b i++ i++ i {
            total = k * i;
            if(total >= a && total <= b) {
                System.out.println("OK");
                break;
            }
            if(total >= b) {
                System.out.println("NG");
                break;
            }
        } {
            total = k * i;
            if(total >= a && total <= b) {
                System.out.println("OK");
                break;
            }
            if(total >= b) {
                System.out.println("NG");
                break;
            }
        } total = k * i total k * i k i if(total >= a && total <= b) {
                System.out.println("OK");
                break;
            } total >= a && total <= b total >= a total a total <= b total b {
                System.out.println("OK");
                break;
            } System.out.println("OK") System.out.println System.out System System.out "OK" break; if(total >= b) {
                System.out.println("NG");
                break;
            } total >= b total b {
                System.out.println("NG");
                break;
            } System.out.println("NG") System.out.println System.out System System.out "NG" break; String[] args args public class Main {
    public static void main(String[] args) {
        //コード
        Scanner scanner = new Scanner(System.in);
        Integer k = Integer.parseInt(scanner.next());
        Integer a = Integer.parseInt(scanner.next());
        Integer b = Integer.parseInt(scanner.next());


        int total = 0;
        for(int i = 1; i <= b; i++) {
            total = k * i;
            if(total >= a && total <= b) {
                System.out.println("OK");
                break;
            }
            if(total >= b) {
                System.out.println("NG");
                break;
            }
        }
    }
} public class Main {
    public static void main(String[] args) {
        //コード
        Scanner scanner = new Scanner(System.in);
        Integer k = Integer.parseInt(scanner.next());
        Integer a = Integer.parseInt(scanner.next());
        Integer b = Integer.parseInt(scanner.next());


        int total = 0;
        for(int i = 1; i <= b; i++) {
            total = k * i;
            if(total >= a && total <= b) {
                System.out.println("OK");
                break;
            }
            if(total >= b) {
                System.out.println("NG");
                break;
            }
        }
    }
} Main

import java.util.Scanner;
import java.util.Arrays;
import java.util.stream.*;

public class Main {
    public static void main(String[] args) {
        //コード
        Scanner scanner = new Scanner(System.in);
        Integer k = Integer.parseInt(scanner.next());
        Integer a = Integer.parseInt(scanner.next());
        Integer b = Integer.parseInt(scanner.next());


        int total = 0;
        for(int i = 1; i <= b; i++) {
            total = k * i;
            if(total >= a && total <= b) {
                System.out.println("OK");
                break;
            }
            if(total >= b) {
                System.out.println("NG");
                break;
            }
        }
    }
}
