import java.util.Scanner;

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        
        int K = sc.nextInt();
        int A = sc.nextInt();
        int B = sc.nextInt();

        boolean TF = false;
        
        for (int i = A; i <= B; i++) {
            if(i % K == 0) {
                TF = true;
                break;
            } 
        }

        if (TF) {
            System.out.println("OK");
        } else {
            System.out.println("NG");
        }
    }
} import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        
        int K = sc.nextInt();
        int A = sc.nextInt();
        int B = sc.nextInt();

        boolean TF = false;
        
        for (int i = A; i <= B; i++) {
            if(i % K == 0) {
                TF = true;
                break;
            } 
        }

        if (TF) {
            System.out.println("OK");
        } else {
            System.out.println("NG");
        }
    }
} Main public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        
        int K = sc.nextInt();
        int A = sc.nextInt();
        int B = sc.nextInt();

        boolean TF = false;
        
        for (int i = A; i <= B; i++) {
            if(i % K == 0) {
                TF = true;
                break;
            } 
        }

        if (TF) {
            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();

        boolean TF = false;
        
        for (int i = A; i <= B; i++) {
            if(i % K == 0) {
                TF = true;
                break;
            } 
        }

        if (TF) {
            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 boolean TF = false; TF false for (int i = A; i <= B; i++) {
            if(i % K == 0) {
                TF = true;
                break;
            } 
        } int i = A; int i = A; i A i <= B i B i++ i++ i {
            if(i % K == 0) {
                TF = true;
                break;
            } 
        } {
            if(i % K == 0) {
                TF = true;
                break;
            } 
        } if(i % K == 0) {
                TF = true;
                break;
            } i % K == 0 i % K i K 0 {
                TF = true;
                break;
            } TF = true TF true break; if (TF) {
            System.out.println("OK");
        } else {
            System.out.println("NG");
        } TF {
            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 public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        
        int K = sc.nextInt();
        int A = sc.nextInt();
        int B = sc.nextInt();

        boolean TF = false;
        
        for (int i = A; i <= B; i++) {
            if(i % K == 0) {
                TF = true;
                break;
            } 
        }

        if (TF) {
            System.out.println("OK");
        } else {
            System.out.println("NG");
        }
    }
} public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        
        int K = sc.nextInt();
        int A = sc.nextInt();
        int B = sc.nextInt();

        boolean TF = false;
        
        for (int i = A; i <= B; i++) {
            if(i % K == 0) {
                TF = true;
                break;
            } 
        }

        if (TF) {
            System.out.println("OK");
        } else {
            System.out.println("NG");
        }
    }
} Main
import java.util.Scanner;

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        
        int K = sc.nextInt();
        int A = sc.nextInt();
        int B = sc.nextInt();

        boolean TF = false;
        
        for (int i = A; i <= B; i++) {
            if(i % K == 0) {
                TF = true;
                break;
            } 
        }

        if (TF) {
            System.out.println("OK");
        } else {
            System.out.println("NG");
        }
    }
}
