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 AmodK = A % K;
        if (((B - A) >= (K - AmodK)) || (AmodK == 0)) {
            System.out.println("OK");
        } else {
            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 AmodK = A % K;
        if (((B - A) >= (K - AmodK)) || (AmodK == 0)) {
            System.out.println("OK");
        } else {
            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 AmodK = A % K;
        if (((B - A) >= (K - AmodK)) || (AmodK == 0)) {
            System.out.println("OK");
        } else {
            System.out.println("NG");
        }
    } main {
        Scanner sc = new Scanner(System.in);
        int K = sc.nextInt();
        int A = sc.nextInt();
        int B = sc.nextInt();
        int AmodK = A % K;
        if (((B - A) >= (K - AmodK)) || (AmodK == 0)) {
            System.out.println("OK");
        } else {
            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 AmodK = A % K; AmodK A % K A K if (((B - A) >= (K - AmodK)) || (AmodK == 0)) {
            System.out.println("OK");
        } else {
            System.out.println("NG");
        } ((B - A) >= (K - AmodK)) || (AmodK == 0) ((B - A) >= (K - AmodK)) (B - A) B A (K - AmodK) K AmodK (AmodK == 0) AmodK 0 {
            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" 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 AmodK = A % K;
        if (((B - A) >= (K - AmodK)) || (AmodK == 0)) {
            System.out.println("OK");
        } else {
            System.out.println("NG");
        }
    }
}