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();
        for(int i=1; i<=1000; i++) {
            if(k * i >= a && k * i <=b) {
                System.out.println("OK");
                return;
            }
        }
        System.out.println("NG");
    }
} 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();
        for(int i=1; i<=1000; i++) {
            if(k * i >= a && k * i <=b) {
                System.out.println("OK");
                return;
            }
        }
        System.out.println("NG");
    }
} 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();
        for(int i=1; i<=1000; i++) {
            if(k * i >= a && k * i <=b) {
                System.out.println("OK");
                return;
            }
        }
        System.out.println("NG");
    } main {
        Scanner sc = new Scanner(System.in);
        int k = sc.nextInt();
        int a = sc.nextInt();
        int b = sc.nextInt();
        for(int i=1; i<=1000; i++) {
            if(k * i >= a && k * i <=b) {
                System.out.println("OK");
                return;
            }
        }
        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 for(int i=1; i<=1000; i++) {
            if(k * i >= a && k * i <=b) {
                System.out.println("OK");
                return;
            }
        } int i=1; int i=1; i 1 i<=1000 i 1000 i++ i++ i {
            if(k * i >= a && k * i <=b) {
                System.out.println("OK");
                return;
            }
        } {
            if(k * i >= a && k * i <=b) {
                System.out.println("OK");
                return;
            }
        } if(k * i >= a && k * i <=b) {
                System.out.println("OK");
                return;
            } k * i >= a && k * i <=b k * i >= a k * i k i a k * i <=b k * i k i b {
                System.out.println("OK");
                return;
            } System.out.println("OK") System.out.println System.out System System.out "OK" return; 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);
        int k = sc.nextInt();
        int a = sc.nextInt();
        int b = sc.nextInt();
        for(int i=1; i<=1000; i++) {
            if(k * i >= a && k * i <=b) {
                System.out.println("OK");
                return;
            }
        }
        System.out.println("NG");
    }
} 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();
        for(int i=1; i<=1000; i++) {
            if(k * i >= a && k * i <=b) {
                System.out.println("OK");
                return;
            }
        }
        System.out.println("NG");
    }
} 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();
        for(int i=1; i<=1000; i++) {
            if(k * i >= a && k * i <=b) {
                System.out.println("OK");
                return;
            }
        }
        System.out.println("NG");
    }
}