import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.*;


public class Main {
    private static int MOD = 1000000007;


    public static void main(String[] args) throws IOException {
        InputStreamReader isr = new InputStreamReader(System.in);
        BufferedReader br = new BufferedReader(isr);
        Integer k = Integer.parseInt(br.readLine());
        String str = br.readLine();
        String[] s = str.split(" ");
        int a = Integer.parseInt(s[0]);
        int b = Integer.parseInt(s[1]);

        for (int i = a; i <= b; i++) {
            if(i % k == 0 ){
                System.out.println("OK");
                return;
            }
        }
        System.out.println("NG");
    }


} import java.io.BufferedReader; BufferedReader java.io import java.io.IOException; IOException java.io import java.io.InputStreamReader; InputStreamReader java.io import java.util.*; util.* java public class Main {
    private static int MOD = 1000000007;


    public static void main(String[] args) throws IOException {
        InputStreamReader isr = new InputStreamReader(System.in);
        BufferedReader br = new BufferedReader(isr);
        Integer k = Integer.parseInt(br.readLine());
        String str = br.readLine();
        String[] s = str.split(" ");
        int a = Integer.parseInt(s[0]);
        int b = Integer.parseInt(s[1]);

        for (int i = a; i <= b; i++) {
            if(i % k == 0 ){
                System.out.println("OK");
                return;
            }
        }
        System.out.println("NG");
    }


} Main private static int MOD = 1000000007; MOD 1000000007 public static void main(String[] args) throws IOException {
        InputStreamReader isr = new InputStreamReader(System.in);
        BufferedReader br = new BufferedReader(isr);
        Integer k = Integer.parseInt(br.readLine());
        String str = br.readLine();
        String[] s = str.split(" ");
        int a = Integer.parseInt(s[0]);
        int b = Integer.parseInt(s[1]);

        for (int i = a; i <= b; i++) {
            if(i % k == 0 ){
                System.out.println("OK");
                return;
            }
        }
        System.out.println("NG");
    } main {
        InputStreamReader isr = new InputStreamReader(System.in);
        BufferedReader br = new BufferedReader(isr);
        Integer k = Integer.parseInt(br.readLine());
        String str = br.readLine();
        String[] s = str.split(" ");
        int a = Integer.parseInt(s[0]);
        int b = Integer.parseInt(s[1]);

        for (int i = a; i <= b; i++) {
            if(i % k == 0 ){
                System.out.println("OK");
                return;
            }
        }
        System.out.println("NG");
    } InputStreamReader isr = new InputStreamReader(System.in); isr new InputStreamReader(System.in) BufferedReader br = new BufferedReader(isr); br new BufferedReader(isr) Integer k = Integer.parseInt(br.readLine()); k Integer.parseInt(br.readLine()) Integer.parseInt Integer br.readLine() br.readLine br String str = br.readLine(); str br.readLine() br.readLine br String[] s = str.split(" "); s str.split(" ") str.split str " " 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 for (int i = a; i <= b; i++) {
            if(i % k == 0 ){
                System.out.println("OK");
                return;
            }
        } int i = a; int i = a; i a i <= b i b i++ i++ i {
            if(i % k == 0 ){
                System.out.println("OK");
                return;
            }
        } {
            if(i % k == 0 ){
                System.out.println("OK");
                return;
            }
        } if(i % k == 0 ){
                System.out.println("OK");
                return;
            } i % k == 0 i % k i k 0 {
                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 {
    private static int MOD = 1000000007;


    public static void main(String[] args) throws IOException {
        InputStreamReader isr = new InputStreamReader(System.in);
        BufferedReader br = new BufferedReader(isr);
        Integer k = Integer.parseInt(br.readLine());
        String str = br.readLine();
        String[] s = str.split(" ");
        int a = Integer.parseInt(s[0]);
        int b = Integer.parseInt(s[1]);

        for (int i = a; i <= b; i++) {
            if(i % k == 0 ){
                System.out.println("OK");
                return;
            }
        }
        System.out.println("NG");
    }


} public class Main {
    private static int MOD = 1000000007;


    public static void main(String[] args) throws IOException {
        InputStreamReader isr = new InputStreamReader(System.in);
        BufferedReader br = new BufferedReader(isr);
        Integer k = Integer.parseInt(br.readLine());
        String str = br.readLine();
        String[] s = str.split(" ");
        int a = Integer.parseInt(s[0]);
        int b = Integer.parseInt(s[1]);

        for (int i = a; i <= b; i++) {
            if(i % k == 0 ){
                System.out.println("OK");
                return;
            }
        }
        System.out.println("NG");
    }


} Main
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.*;


public class Main {
    private static int MOD = 1000000007;


    public static void main(String[] args) throws IOException {
        InputStreamReader isr = new InputStreamReader(System.in);
        BufferedReader br = new BufferedReader(isr);
        Integer k = Integer.parseInt(br.readLine());
        String str = br.readLine();
        String[] s = str.split(" ");
        int a = Integer.parseInt(s[0]);
        int b = Integer.parseInt(s[1]);

        for (int i = a; i <= b; i++) {
            if(i % k == 0 ){
                System.out.println("OK");
                return;
            }
        }
        System.out.println("NG");
    }


}
