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

public 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();

        boolean ok = false;
        if(a %k ==0 || b%k == 0) ok = true;
        if(!ok){
            int r = a % k;
            int temp = a- r;
            for(int i=temp; i<b; i+=k){
                if(i > a && i%k == 0){
                    ok = true;
                    break;
                }
            }

        }
        if(ok) System.out.println("OK");
        else System.out.println("NG");
    }
} import java.io.*; io.* java import java.util.*; util.* java public 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();

        boolean ok = false;
        if(a %k ==0 || b%k == 0) ok = true;
        if(!ok){
            int r = a % k;
            int temp = a- r;
            for(int i=temp; i<b; i+=k){
                if(i > a && i%k == 0){
                    ok = true;
                    break;
                }
            }

        }
        if(ok) 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();

        boolean ok = false;
        if(a %k ==0 || b%k == 0) ok = true;
        if(!ok){
            int r = a % k;
            int temp = a- r;
            for(int i=temp; i<b; i+=k){
                if(i > a && i%k == 0){
                    ok = true;
                    break;
                }
            }

        }
        if(ok) 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 ok = false;
        if(a %k ==0 || b%k == 0) ok = true;
        if(!ok){
            int r = a % k;
            int temp = a- r;
            for(int i=temp; i<b; i+=k){
                if(i > a && i%k == 0){
                    ok = true;
                    break;
                }
            }

        }
        if(ok) 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 ok = false; ok false if(a %k ==0 || b%k == 0) ok = true; a %k ==0 || b%k == 0 a %k ==0 a %k a k 0 b%k == 0 b%k b k 0 ok = true ok true if(!ok){
            int r = a % k;
            int temp = a- r;
            for(int i=temp; i<b; i+=k){
                if(i > a && i%k == 0){
                    ok = true;
                    break;
                }
            }

        } !ok ok {
            int r = a % k;
            int temp = a- r;
            for(int i=temp; i<b; i+=k){
                if(i > a && i%k == 0){
                    ok = true;
                    break;
                }
            }

        } int r = a % k; r a % k a k int temp = a- r; temp a- r a r for(int i=temp; i<b; i+=k){
                if(i > a && i%k == 0){
                    ok = true;
                    break;
                }
            } int i=temp; int i=temp; i temp i<b i b i+=k i+=k i k {
                if(i > a && i%k == 0){
                    ok = true;
                    break;
                }
            } {
                if(i > a && i%k == 0){
                    ok = true;
                    break;
                }
            } if(i > a && i%k == 0){
                    ok = true;
                    break;
                } i > a && i%k == 0 i > a i a i%k == 0 i%k i k 0 {
                    ok = true;
                    break;
                } ok = true ok true break; if(ok) System.out.println("OK");
        else System.out.println("NG"); ok System.out.println("OK") System.out.println System.out System System.out "OK" 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){
        Scanner sc =new Scanner(System.in);
        int k = sc.nextInt();
        int a = sc.nextInt();
        int b = sc.nextInt();

        boolean ok = false;
        if(a %k ==0 || b%k == 0) ok = true;
        if(!ok){
            int r = a % k;
            int temp = a- r;
            for(int i=temp; i<b; i+=k){
                if(i > a && i%k == 0){
                    ok = true;
                    break;
                }
            }

        }
        if(ok) System.out.println("OK");
        else System.out.println("NG");
    }
} public 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();

        boolean ok = false;
        if(a %k ==0 || b%k == 0) ok = true;
        if(!ok){
            int r = a % k;
            int temp = a- r;
            for(int i=temp; i<b; i+=k){
                if(i > a && i%k == 0){
                    ok = true;
                    break;
                }
            }

        }
        if(ok) System.out.println("OK");
        else System.out.println("NG");
    }
} Main
import java.io.*;
import java.util.*;

public 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();

        boolean ok = false;
        if(a %k ==0 || b%k == 0) ok = true;
        if(!ok){
            int r = a % k;
            int temp = a- r;
            for(int i=temp; i<b; i+=k){
                if(i > a && i%k == 0){
                    ok = true;
                    break;
                }
            }

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