import java.util.*;

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();

        int n = 1;
        while_LB:
        while (n <= 1000) {
            for (int i = 1; i <= 1000; i++) {
                n = K * i;
                if (n >= A && n <= B) {
                    System.out.println("OK");
                    break while_LB;
                }

            }
            System.out.println("NG");
        }
    }
} import java.util.*; util.* java 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();

        int n = 1;
        while_LB:
        while (n <= 1000) {
            for (int i = 1; i <= 1000; i++) {
                n = K * i;
                if (n >= A && n <= B) {
                    System.out.println("OK");
                    break while_LB;
                }

            }
            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();

        int n = 1;
        while_LB:
        while (n <= 1000) {
            for (int i = 1; i <= 1000; i++) {
                n = K * i;
                if (n >= A && n <= B) {
                    System.out.println("OK");
                    break while_LB;
                }

            }
            System.out.println("NG");
        }
    } main {
        Scanner sc = new Scanner(System.in);
        int K = sc.nextInt();
        int A = sc.nextInt();
        int B = sc.nextInt();

        int n = 1;
        while_LB:
        while (n <= 1000) {
            for (int i = 1; i <= 1000; i++) {
                n = K * i;
                if (n >= A && n <= B) {
                    System.out.println("OK");
                    break while_LB;
                }

            }
            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 n = 1; n 1 String[] args args
import java.util.*;

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();

        int n = 1;
        while_LB:
        while (n <= 1000) {
            for (int i = 1; i <= 1000; i++) {
                n = K * i;
                if (n >= A && n <= B) {
                    System.out.println("OK");
                    break while_LB;
                }

            }
            System.out.println("NG");
        }
    }
}
