import java.io.*;
import java.util.*;

public class Main {
    public static void main(String[] args) throws IOException {
        OutputStream outputStream = System.out;
        PrintWriter out = new PrintWriter(outputStream);
        FastReader in = new FastReader();
        test a=new test();
        a.solve(in,out);
        out.close();
    }
}
class test{
    public void solve(FastReader in, PrintWriter out){
        int k=in.nextInt();
        int a=in.nextInt();
        int b=in.nextInt();
        boolean f =true;
        for(int i=a;i<=b;i++){
            if(i%k==0){
                out.println("OK");
                f=false;
                break;
            }
        }
        if(f){
            out.println("NG");
        }
    }
    public boolean src(int a[],int b[],int k,int l){
        for(int i=0;i<a.length;i++){
            if(a[i]==k && b[i]==l){
                return true;
            }
        }
        return false;
    }
    public int search(ArrayList<Integer> my){
        int max=my.get(0);
        int k=0;
        for(int i=1;i<my.size();i++){
            if(my.get(i)>max){
                max=my.get(i);
                k=i;
            }
        }
        return k;
    }
}

class FastReader{
    BufferedReader br;
    StringTokenizer st;

    public FastReader(){
        br = new BufferedReader(new InputStreamReader(System.in));
    }

    String next(){
        while(st==null || !st.hasMoreElements()){
            try{
                st=new StringTokenizer(br.readLine());
            }
            catch(IOException e){
                e.printStackTrace();
            }
        }
        return st.nextToken();
    }

    int nextInt(){
        return Integer.parseInt(next());
    }

    Long nextLong(){
        return Long.parseLong(next());
    }

    double nextDouble(){
        return Double.parseDouble(next());
    }
    String nextLine(){
        String str="";
        try{
            str=br.readLine();
        }
        catch(IOException e){
            e.printStackTrace();
        }
        return str;
    }
}
 import java.io.*; io.* java import java.util.*; util.* java public class Main {
    public static void main(String[] args) throws IOException {
        OutputStream outputStream = System.out;
        PrintWriter out = new PrintWriter(outputStream);
        FastReader in = new FastReader();
        test a=new test();
        a.solve(in,out);
        out.close();
    }
} Main public static void main(String[] args) throws IOException {
        OutputStream outputStream = System.out;
        PrintWriter out = new PrintWriter(outputStream);
        FastReader in = new FastReader();
        test a=new test();
        a.solve(in,out);
        out.close();
    } main {
        OutputStream outputStream = System.out;
        PrintWriter out = new PrintWriter(outputStream);
        FastReader in = new FastReader();
        test a=new test();
        a.solve(in,out);
        out.close();
    } OutputStream outputStream = System.out; outputStream System.out System System.out PrintWriter out = new PrintWriter(outputStream); out new PrintWriter(outputStream) FastReader in = new FastReader(); in new FastReader() test a=new test(); a new test() a.solve(in,out) a.solve a in out out.close() out.close out String[] args args class test{
    public void solve(FastReader in, PrintWriter out){
        int k=in.nextInt();
        int a=in.nextInt();
        int b=in.nextInt();
        boolean f =true;
        for(int i=a;i<=b;i++){
            if(i%k==0){
                out.println("OK");
                f=false;
                break;
            }
        }
        if(f){
            out.println("NG");
        }
    }
    public boolean src(int a[],int b[],int k,int l){
        for(int i=0;i<a.length;i++){
            if(a[i]==k && b[i]==l){
                return true;
            }
        }
        return false;
    }
    public int search(ArrayList<Integer> my){
        int max=my.get(0);
        int k=0;
        for(int i=1;i<my.size();i++){
            if(my.get(i)>max){
                max=my.get(i);
                k=i;
            }
        }
        return k;
    }
} test public void solve(FastReader in, PrintWriter out){
        int k=in.nextInt();
        int a=in.nextInt();
        int b=in.nextInt();
        boolean f =true;
        for(int i=a;i<=b;i++){
            if(i%k==0){
                out.println("OK");
                f=false;
                break;
            }
        }
        if(f){
            out.println("NG");
        }
    } solve {
        int k=in.nextInt();
        int a=in.nextInt();
        int b=in.nextInt();
        boolean f =true;
        for(int i=a;i<=b;i++){
            if(i%k==0){
                out.println("OK");
                f=false;
                break;
            }
        }
        if(f){
            out.println("NG");
        }
    } int k=in.nextInt(); k in.nextInt() in.nextInt in int a=in.nextInt(); a in.nextInt() in.nextInt in int b=in.nextInt(); b in.nextInt() in.nextInt in boolean f =true; f true for(int i=a;i<=b;i++){
            if(i%k==0){
                out.println("OK");
                f=false;
                break;
            }
        } int i=a; int i=a; i a i<=b i b i++ i++ i {
            if(i%k==0){
                out.println("OK");
                f=false;
                break;
            }
        } {
            if(i%k==0){
                out.println("OK");
                f=false;
                break;
            }
        } if(i%k==0){
                out.println("OK");
                f=false;
                break;
            } i%k==0 i%k i k 0 {
                out.println("OK");
                f=false;
                break;
            } out.println("OK") out.println out "OK" f=false f false break; if(f){
            out.println("NG");
        } f {
            out.println("NG");
        } out.println("NG") out.println out "NG" FastReader in in PrintWriter out out public boolean src(int a[],int b[],int k,int l){
        for(int i=0;i<a.length;i++){
            if(a[i]==k && b[i]==l){
                return true;
            }
        }
        return false;
    } src {
        for(int i=0;i<a.length;i++){
            if(a[i]==k && b[i]==l){
                return true;
            }
        }
        return false;
    } for(int i=0;i<a.length;i++){
            if(a[i]==k && b[i]==l){
                return true;
            }
        } int i=0; int i=0; i 0 i<a.length i a.length a a.length i++ i++ i {
            if(a[i]==k && b[i]==l){
                return true;
            }
        } {
            if(a[i]==k && b[i]==l){
                return true;
            }
        } if(a[i]==k && b[i]==l){
                return true;
            } a[i]==k && b[i]==l a[i]==k a[i] a i k b[i]==l b[i] b i l {
                return true;
            } return true; true return false; false int a[] a int b[] b int k k int l l public int search(ArrayList<Integer> my){
        int max=my.get(0);
        int k=0;
        for(int i=1;i<my.size();i++){
            if(my.get(i)>max){
                max=my.get(i);
                k=i;
            }
        }
        return k;
    } search {
        int max=my.get(0);
        int k=0;
        for(int i=1;i<my.size();i++){
            if(my.get(i)>max){
                max=my.get(i);
                k=i;
            }
        }
        return k;
    } int max=my.get(0); max my.get(0) my.get my 0 int k=0; k 0 for(int i=1;i<my.size();i++){
            if(my.get(i)>max){
                max=my.get(i);
                k=i;
            }
        } int i=1; int i=1; i 1 i<my.size() i my.size() my.size my i++ i++ i {
            if(my.get(i)>max){
                max=my.get(i);
                k=i;
            }
        } {
            if(my.get(i)>max){
                max=my.get(i);
                k=i;
            }
        } if(my.get(i)>max){
                max=my.get(i);
                k=i;
            } my.get(i)>max my.get(i) my.get my i max {
                max=my.get(i);
                k=i;
            } max=my.get(i) max my.get(i) my.get my i k=i k i return k; k ArrayList<Integer> my my class FastReader{
    BufferedReader br;
    StringTokenizer st;

    public FastReader(){
        br = new BufferedReader(new InputStreamReader(System.in));
    }

    String next(){
        while(st==null || !st.hasMoreElements()){
            try{
                st=new StringTokenizer(br.readLine());
            }
            catch(IOException e){
                e.printStackTrace();
            }
        }
        return st.nextToken();
    }

    int nextInt(){
        return Integer.parseInt(next());
    }

    Long nextLong(){
        return Long.parseLong(next());
    }

    double nextDouble(){
        return Double.parseDouble(next());
    }
    String nextLine(){
        String str="";
        try{
            str=br.readLine();
        }
        catch(IOException e){
            e.printStackTrace();
        }
        return str;
    }
} FastReader BufferedReader br; br StringTokenizer st; st public FastReader(){
        br = new BufferedReader(new InputStreamReader(System.in));
    } FastReader {
        br = new BufferedReader(new InputStreamReader(System.in));
    } br = new BufferedReader(new InputStreamReader(System.in)) br new BufferedReader(new InputStreamReader(System.in)) String next(){
        while(st==null || !st.hasMoreElements()){
            try{
                st=new StringTokenizer(br.readLine());
            }
            catch(IOException e){
                e.printStackTrace();
            }
        }
        return st.nextToken();
    } next {
        while(st==null || !st.hasMoreElements()){
            try{
                st=new StringTokenizer(br.readLine());
            }
            catch(IOException e){
                e.printStackTrace();
            }
        }
        return st.nextToken();
    } while(st==null || !st.hasMoreElements()){
            try{
                st=new StringTokenizer(br.readLine());
            }
            catch(IOException e){
                e.printStackTrace();
            }
        } st==null || !st.hasMoreElements() st==null st null !st.hasMoreElements() st.hasMoreElements() st.hasMoreElements st {
            try{
                st=new StringTokenizer(br.readLine());
            }
            catch(IOException e){
                e.printStackTrace();
            }
        } try{
                st=new StringTokenizer(br.readLine());
            }
            catch(IOException e){
                e.printStackTrace();
            } catch(IOException e){
                e.printStackTrace();
            } IOException e {
                e.printStackTrace();
            } e.printStackTrace() e.printStackTrace e {
                st=new StringTokenizer(br.readLine());
            } st=new StringTokenizer(br.readLine()) st new StringTokenizer(br.readLine()) return st.nextToken(); st.nextToken() st.nextToken st int nextInt(){
        return Integer.parseInt(next());
    } nextInt {
        return Integer.parseInt(next());
    } return Integer.parseInt(next()); Integer.parseInt(next()) Integer.parseInt Integer next() next Long nextLong(){
        return Long.parseLong(next());
    } nextLong {
        return Long.parseLong(next());
    } return Long.parseLong(next()); Long.parseLong(next()) Long.parseLong Long next() next double nextDouble(){
        return Double.parseDouble(next());
    } nextDouble {
        return Double.parseDouble(next());
    } return Double.parseDouble(next()); Double.parseDouble(next()) Double.parseDouble Double next() next String nextLine(){
        String str="";
        try{
            str=br.readLine();
        }
        catch(IOException e){
            e.printStackTrace();
        }
        return str;
    } nextLine {
        String str="";
        try{
            str=br.readLine();
        }
        catch(IOException e){
            e.printStackTrace();
        }
        return str;
    } String str=""; str "" try{
            str=br.readLine();
        }
        catch(IOException e){
            e.printStackTrace();
        } catch(IOException e){
            e.printStackTrace();
        } IOException e {
            e.printStackTrace();
        } e.printStackTrace() e.printStackTrace e {
            str=br.readLine();
        } str=br.readLine() str br.readLine() br.readLine br return str; str public class Main {
    public static void main(String[] args) throws IOException {
        OutputStream outputStream = System.out;
        PrintWriter out = new PrintWriter(outputStream);
        FastReader in = new FastReader();
        test a=new test();
        a.solve(in,out);
        out.close();
    }
} public class Main {
    public static void main(String[] args) throws IOException {
        OutputStream outputStream = System.out;
        PrintWriter out = new PrintWriter(outputStream);
        FastReader in = new FastReader();
        test a=new test();
        a.solve(in,out);
        out.close();
    }
} Main
import java.io.*;
import java.util.*;

public class Main {
    public static void main(String[] args) throws IOException {
        OutputStream outputStream = System.out;
        PrintWriter out = new PrintWriter(outputStream);
        FastReader in = new FastReader();
        test a=new test();
        a.solve(in,out);
        out.close();
    }
}
class test{
    public void solve(FastReader in, PrintWriter out){
        int k=in.nextInt();
        int a=in.nextInt();
        int b=in.nextInt();
        boolean f =true;
        for(int i=a;i<=b;i++){
            if(i%k==0){
                out.println("OK");
                f=false;
                break;
            }
        }
        if(f){
            out.println("NG");
        }
    }
    public boolean src(int a[],int b[],int k,int l){
        for(int i=0;i<a.length;i++){
            if(a[i]==k && b[i]==l){
                return true;
            }
        }
        return false;
    }
    public int search(ArrayList<Integer> my){
        int max=my.get(0);
        int k=0;
        for(int i=1;i<my.size();i++){
            if(my.get(i)>max){
                max=my.get(i);
                k=i;
            }
        }
        return k;
    }
}

class FastReader{
    BufferedReader br;
    StringTokenizer st;

    public FastReader(){
        br = new BufferedReader(new InputStreamReader(System.in));
    }

    String next(){
        while(st==null || !st.hasMoreElements()){
            try{
                st=new StringTokenizer(br.readLine());
            }
            catch(IOException e){
                e.printStackTrace();
            }
        }
        return st.nextToken();
    }

    int nextInt(){
        return Integer.parseInt(next());
    }

    Long nextLong(){
        return Long.parseLong(next());
    }

    double nextDouble(){
        return Double.parseDouble(next());
    }
    String nextLine(){
        String str="";
        try{
            str=br.readLine();
        }
        catch(IOException e){
            e.printStackTrace();
        }
        return str;
    }
}

