import java.util.*;

public class Main {
    public static void main(final String[] args) {
        final Scanner sc = new Scanner(System.in);
        // 目標値K
        int K = sc.nextInt();
        // 範囲A,B
        int A = sc.nextInt();       
        int B = sc.nextInt();

        int WariFlag=0;

        if( K>B){
        }else{
            for(int i=A;i<=B&&WariFlag==0;i++){
                if(i%K==0){
                   WariFlag=1;
                }
            }
        }
        if(WariFlag==0){
            System.out.println("NG");
        }else{
            System.out.println("OK");
        }

        }
} import java.util.*; util.* java public class Main {
    public static void main(final String[] args) {
        final Scanner sc = new Scanner(System.in);
        // 目標値K
        int K = sc.nextInt();
        // 範囲A,B
        int A = sc.nextInt();       
        int B = sc.nextInt();

        int WariFlag=0;

        if( K>B){
        }else{
            for(int i=A;i<=B&&WariFlag==0;i++){
                if(i%K==0){
                   WariFlag=1;
                }
            }
        }
        if(WariFlag==0){
            System.out.println("NG");
        }else{
            System.out.println("OK");
        }

        }
} Main public static void main(final String[] args) {
        final Scanner sc = new Scanner(System.in);
        // 目標値K
        int K = sc.nextInt();
        // 範囲A,B
        int A = sc.nextInt();       
        int B = sc.nextInt();

        int WariFlag=0;

        if( K>B){
        }else{
            for(int i=A;i<=B&&WariFlag==0;i++){
                if(i%K==0){
                   WariFlag=1;
                }
            }
        }
        if(WariFlag==0){
            System.out.println("NG");
        }else{
            System.out.println("OK");
        }

        } main {
        final Scanner sc = new Scanner(System.in);
        // 目標値K
        int K = sc.nextInt();
        // 範囲A,B
        int A = sc.nextInt();       
        int B = sc.nextInt();

        int WariFlag=0;

        if( K>B){
        }else{
            for(int i=A;i<=B&&WariFlag==0;i++){
                if(i%K==0){
                   WariFlag=1;
                }
            }
        }
        if(WariFlag==0){
            System.out.println("NG");
        }else{
            System.out.println("OK");
        }

        } final 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 int WariFlag=0; WariFlag 0 if( K>B){
        }else{
            for(int i=A;i<=B&&WariFlag==0;i++){
                if(i%K==0){
                   WariFlag=1;
                }
            }
        } K>B K B {
        } {
            for(int i=A;i<=B&&WariFlag==0;i++){
                if(i%K==0){
                   WariFlag=1;
                }
            }
        } for(int i=A;i<=B&&WariFlag==0;i++){
                if(i%K==0){
                   WariFlag=1;
                }
            } int i=A; int i=A; i A i<=B&&WariFlag==0 i<=B i B WariFlag==0 WariFlag 0 i++ i++ i {
                if(i%K==0){
                   WariFlag=1;
                }
            } {
                if(i%K==0){
                   WariFlag=1;
                }
            } if(i%K==0){
                   WariFlag=1;
                } i%K==0 i%K i K 0 {
                   WariFlag=1;
                } WariFlag=1 WariFlag 1 if(WariFlag==0){
            System.out.println("NG");
        }else{
            System.out.println("OK");
        } WariFlag==0 WariFlag 0 {
            System.out.println("NG");
        } System.out.println("NG") System.out.println System.out System System.out "NG" {
            System.out.println("OK");
        } System.out.println("OK") System.out.println System.out System System.out "OK" final String[] args args public class Main {
    public static void main(final String[] args) {
        final Scanner sc = new Scanner(System.in);
        // 目標値K
        int K = sc.nextInt();
        // 範囲A,B
        int A = sc.nextInt();       
        int B = sc.nextInt();

        int WariFlag=0;

        if( K>B){
        }else{
            for(int i=A;i<=B&&WariFlag==0;i++){
                if(i%K==0){
                   WariFlag=1;
                }
            }
        }
        if(WariFlag==0){
            System.out.println("NG");
        }else{
            System.out.println("OK");
        }

        }
} public class Main {
    public static void main(final String[] args) {
        final Scanner sc = new Scanner(System.in);
        // 目標値K
        int K = sc.nextInt();
        // 範囲A,B
        int A = sc.nextInt();       
        int B = sc.nextInt();

        int WariFlag=0;

        if( K>B){
        }else{
            for(int i=A;i<=B&&WariFlag==0;i++){
                if(i%K==0){
                   WariFlag=1;
                }
            }
        }
        if(WariFlag==0){
            System.out.println("NG");
        }else{
            System.out.println("OK");
        }

        }
} Main
import java.util.*;

public class Main {
    public static void main(final String[] args) {
        final Scanner sc = new Scanner(System.in);
        // 目標値K
        int K = sc.nextInt();
        // 範囲A,B
        int A = sc.nextInt();       
        int B = sc.nextInt();

        int WariFlag=0;

        if( K>B){
        }else{
            for(int i=A;i<=B&&WariFlag==0;i++){
                if(i%K==0){
                   WariFlag=1;
                }
            }
        }
        if(WariFlag==0){
            System.out.println("NG");
        }else{
            System.out.println("OK");
        }

        }
}
