import java.math.BigInteger;
import java.util.*;
import java.io.*;

public class Main {

    public static void main(String[] args) throws Exception {
        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
        int K = Integer.parseInt(in.readLine());
        String[] s = in.readLine().split(" ");
        int A = Integer.parseInt(s[0]);
        int B = Integer.parseInt(s[1]);
        if(A % K == 0) {
            System.out.println("OK");
        } else {
            int mod = A % K;
            int num = A + (K - mod);
            if(num <= B && num >= A) {
                System.out.println("OK");
            } else {
                System.out.println("NG");
            }
        }
    }
} import java.math.BigInteger; BigInteger java.math import java.util.*; util.* java import java.io.*; io.* java public class Main {

    public static void main(String[] args) throws Exception {
        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
        int K = Integer.parseInt(in.readLine());
        String[] s = in.readLine().split(" ");
        int A = Integer.parseInt(s[0]);
        int B = Integer.parseInt(s[1]);
        if(A % K == 0) {
            System.out.println("OK");
        } else {
            int mod = A % K;
            int num = A + (K - mod);
            if(num <= B && num >= A) {
                System.out.println("OK");
            } else {
                System.out.println("NG");
            }
        }
    }
} Main public static void main(String[] args) throws Exception {
        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
        int K = Integer.parseInt(in.readLine());
        String[] s = in.readLine().split(" ");
        int A = Integer.parseInt(s[0]);
        int B = Integer.parseInt(s[1]);
        if(A % K == 0) {
            System.out.println("OK");
        } else {
            int mod = A % K;
            int num = A + (K - mod);
            if(num <= B && num >= A) {
                System.out.println("OK");
            } else {
                System.out.println("NG");
            }
        }
    } main {
        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
        int K = Integer.parseInt(in.readLine());
        String[] s = in.readLine().split(" ");
        int A = Integer.parseInt(s[0]);
        int B = Integer.parseInt(s[1]);
        if(A % K == 0) {
            System.out.println("OK");
        } else {
            int mod = A % K;
            int num = A + (K - mod);
            if(num <= B && num >= A) {
                System.out.println("OK");
            } else {
                System.out.println("NG");
            }
        }
    } BufferedReader in = new BufferedReader(new InputStreamReader(System.in)); in new BufferedReader(new InputStreamReader(System.in)) int K = Integer.parseInt(in.readLine()); K Integer.parseInt(in.readLine()) Integer.parseInt Integer in.readLine() in.readLine in String[] s = in.readLine().split(" "); s in.readLine().split(" ") in.readLine().split in.readLine() in.readLine in " " int A = Integer.parseInt(s[0]); A Integer.parseInt(s[0]) Integer.parseInt Integer s[0] s 0 int B = Integer.parseInt(s[1]); B Integer.parseInt(s[1]) Integer.parseInt Integer s[1] s 1 if(A % K == 0) {
            System.out.println("OK");
        } else {
            int mod = A % K;
            int num = A + (K - mod);
            if(num <= B && num >= A) {
                System.out.println("OK");
            } else {
                System.out.println("NG");
            }
        } A % K == 0 A % K A K 0 {
            System.out.println("OK");
        } System.out.println("OK") System.out.println System.out System System.out "OK" {
            int mod = A % K;
            int num = A + (K - mod);
            if(num <= B && num >= A) {
                System.out.println("OK");
            } else {
                System.out.println("NG");
            }
        } int mod = A % K; mod A % K A K int num = A + (K - mod); num A + (K - mod) A (K - mod) K mod if(num <= B && num >= A) {
                System.out.println("OK");
            } else {
                System.out.println("NG");
            } num <= B && num >= A num <= B num B num >= A num A {
                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 {
        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
        int K = Integer.parseInt(in.readLine());
        String[] s = in.readLine().split(" ");
        int A = Integer.parseInt(s[0]);
        int B = Integer.parseInt(s[1]);
        if(A % K == 0) {
            System.out.println("OK");
        } else {
            int mod = A % K;
            int num = A + (K - mod);
            if(num <= B && num >= A) {
                System.out.println("OK");
            } else {
                System.out.println("NG");
            }
        }
    }
} public class Main {

    public static void main(String[] args) throws Exception {
        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
        int K = Integer.parseInt(in.readLine());
        String[] s = in.readLine().split(" ");
        int A = Integer.parseInt(s[0]);
        int B = Integer.parseInt(s[1]);
        if(A % K == 0) {
            System.out.println("OK");
        } else {
            int mod = A % K;
            int num = A + (K - mod);
            if(num <= B && num >= A) {
                System.out.println("OK");
            } else {
                System.out.println("NG");
            }
        }
    }
} Main
import java.math.BigInteger;
import java.util.*;
import java.io.*;

public class Main {

    public static void main(String[] args) throws Exception {
        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
        int K = Integer.parseInt(in.readLine());
        String[] s = in.readLine().split(" ");
        int A = Integer.parseInt(s[0]);
        int B = Integer.parseInt(s[1]);
        if(A % K == 0) {
            System.out.println("OK");
        } else {
            int mod = A % K;
            int num = A + (K - mod);
            if(num <= B && num >= A) {
                System.out.println("OK");
            } else {
                System.out.println("NG");
            }
        }
    }
}