import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int k = sc.nextInt();
        int a = sc.nextInt();
        int b = sc.nextInt();
        boolean flg = false;
        for (int i = a; i <= b; i++) {
            if ((i % k) == 0) {
                flg = true;
                break;
            }
        }
        if (flg) {
            System.out.println("OK");
        } else {
            System.out.println("NG");
        }

        sc.close();
    }

} import java.util.Scanner; Scanner java.util public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int k = sc.nextInt();
        int a = sc.nextInt();
        int b = sc.nextInt();
        boolean flg = false;
        for (int i = a; i <= b; i++) {
            if ((i % k) == 0) {
                flg = true;
                break;
            }
        }
        if (flg) {
            System.out.println("OK");
        } else {
            System.out.println("NG");
        }

        sc.close();
    }

} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int k = sc.nextInt();
        int a = sc.nextInt();
        int b = sc.nextInt();
        boolean flg = false;
        for (int i = a; i <= b; i++) {
            if ((i % k) == 0) {
                flg = true;
                break;
            }
        }
        if (flg) {
            System.out.println("OK");
        } else {
            System.out.println("NG");
        }

        sc.close();
    } main {
        Scanner sc = new Scanner(System.in);
        int k = sc.nextInt();
        int a = sc.nextInt();
        int b = sc.nextInt();
        boolean flg = false;
        for (int i = a; i <= b; i++) {
            if ((i % k) == 0) {
                flg = true;
                break;
            }
        }
        if (flg) {
            System.out.println("OK");
        } else {
            System.out.println("NG");
        }

        sc.close();
    } 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 boolean flg = false; flg false for (int i = a; i <= b; i++) {
            if ((i % k) == 0) {
                flg = true;
                break;
            }
        } int i = a; int i = a; i a i <= b i b i++ i++ i {
            if ((i % k) == 0) {
                flg = true;
                break;
            }
        } {
            if ((i % k) == 0) {
                flg = true;
                break;
            }
        } if ((i % k) == 0) {
                flg = true;
                break;
            } (i % k) == 0 (i % k) i k 0 {
                flg = true;
                break;
            } flg = true flg true break; if (flg) {
            System.out.println("OK");
        } else {
            System.out.println("NG");
        } flg {
            System.out.println("OK");
        } System.out.println("OK") System.out.println System.out System System.out "OK" {
            System.out.println("NG");
        } System.out.println("NG") System.out.println System.out System System.out "NG" sc.close() sc.close sc String[] args args public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int k = sc.nextInt();
        int a = sc.nextInt();
        int b = sc.nextInt();
        boolean flg = false;
        for (int i = a; i <= b; i++) {
            if ((i % k) == 0) {
                flg = true;
                break;
            }
        }
        if (flg) {
            System.out.println("OK");
        } else {
            System.out.println("NG");
        }

        sc.close();
    }

} public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int k = sc.nextInt();
        int a = sc.nextInt();
        int b = sc.nextInt();
        boolean flg = false;
        for (int i = a; i <= b; i++) {
            if ((i % k) == 0) {
                flg = true;
                break;
            }
        }
        if (flg) {
            System.out.println("OK");
        } else {
            System.out.println("NG");
        }

        sc.close();
    }

} Main
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int k = sc.nextInt();
        int a = sc.nextInt();
        int b = sc.nextInt();
        boolean flg = false;
        for (int i = a; i <= b; i++) {
            if ((i % k) == 0) {
                flg = true;
                break;
            }
        }
        if (flg) {
            System.out.println("OK");
        } else {
            System.out.println("NG");
        }

        sc.close();
    }

}
