import java.util.*;
import java.math.*;

public class Main {
    static final int MOD = 1_000_000_007; // 10^9+7
    // static final int MAX = 2_147_483_646; // intの最大値
    static final int INF = 1_000_000_000; // 10^9
    static final int MAX = 10_000_000;
    static long[] fact = new long[100];
        public static void main(String args[]) {
        Scanner sc = new Scanner(System.in);
        int k = sc.nextInt();
        int a = sc.nextInt();
        int b = sc.nextInt();
        for(int i = 1;i < 1000;i++){
            if(a<=k*i&&k*i<=b){
                System.out.println("OK");
                return;
            }
        }
        System.out.println("NG");
    }
    
} import java.util.*; util.* java import java.math.*; math.* java public class Main {
    static final int MOD = 1_000_000_007; // 10^9+7
    // static final int MAX = 2_147_483_646; // intの最大値
    static final int INF = 1_000_000_000; // 10^9
    static final int MAX = 10_000_000;
    static long[] fact = new long[100];
        public static void main(String args[]) {
        Scanner sc = new Scanner(System.in);
        int k = sc.nextInt();
        int a = sc.nextInt();
        int b = sc.nextInt();
        for(int i = 1;i < 1000;i++){
            if(a<=k*i&&k*i<=b){
                System.out.println("OK");
                return;
            }
        }
        System.out.println("NG");
    }
    
} Main static final int MOD = 1_000_000_007; // 10^9+7 MOD 1_000_000_007 // static final int MAX = 2_147_483_646; // intの最大値
    static final int INF = 1_000_000_000; // 10^9 INF 1_000_000_000 static final int MAX = 10_000_000; MAX 10_000_000 static long[] fact = new long[100]; fact new long[100] 100 public static void main(String args[]) {
        Scanner sc = new Scanner(System.in);
        int k = sc.nextInt();
        int a = sc.nextInt();
        int b = sc.nextInt();
        for(int i = 1;i < 1000;i++){
            if(a<=k*i&&k*i<=b){
                System.out.println("OK");
                return;
            }
        }
        System.out.println("NG");
    } main {
        Scanner sc = new Scanner(System.in);
        int k = sc.nextInt();
        int a = sc.nextInt();
        int b = sc.nextInt();
        for(int i = 1;i < 1000;i++){
            if(a<=k*i&&k*i<=b){
                System.out.println("OK");
                return;
            }
        }
        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 for(int i = 1;i < 1000;i++){
            if(a<=k*i&&k*i<=b){
                System.out.println("OK");
                return;
            }
        } int i = 1; int i = 1; i 1 i < 1000 i 1000 i++ i++ i {
            if(a<=k*i&&k*i<=b){
                System.out.println("OK");
                return;
            }
        } {
            if(a<=k*i&&k*i<=b){
                System.out.println("OK");
                return;
            }
        } if(a<=k*i&&k*i<=b){
                System.out.println("OK");
                return;
            } a<=k*i&&k*i<=b a<=k*i a k*i k i k*i<=b k*i k i b {
                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 {
    static final int MOD = 1_000_000_007; // 10^9+7
    // static final int MAX = 2_147_483_646; // intの最大値
    static final int INF = 1_000_000_000; // 10^9
    static final int MAX = 10_000_000;
    static long[] fact = new long[100];
        public static void main(String args[]) {
        Scanner sc = new Scanner(System.in);
        int k = sc.nextInt();
        int a = sc.nextInt();
        int b = sc.nextInt();
        for(int i = 1;i < 1000;i++){
            if(a<=k*i&&k*i<=b){
                System.out.println("OK");
                return;
            }
        }
        System.out.println("NG");
    }
    
} public class Main {
    static final int MOD = 1_000_000_007; // 10^9+7
    // static final int MAX = 2_147_483_646; // intの最大値
    static final int INF = 1_000_000_000; // 10^9
    static final int MAX = 10_000_000;
    static long[] fact = new long[100];
        public static void main(String args[]) {
        Scanner sc = new Scanner(System.in);
        int k = sc.nextInt();
        int a = sc.nextInt();
        int b = sc.nextInt();
        for(int i = 1;i < 1000;i++){
            if(a<=k*i&&k*i<=b){
                System.out.println("OK");
                return;
            }
        }
        System.out.println("NG");
    }
    
} Main
import java.util.*;
import java.math.*;

public class Main {
    static final int MOD = 1_000_000_007; // 10^9+7
    // static final int MAX = 2_147_483_646; // intの最大値
    static final int INF = 1_000_000_000; // 10^9
    static final int MAX = 10_000_000;
    static long[] fact = new long[100];
        public static void main(String args[]) {
        Scanner sc = new Scanner(System.in);
        int k = sc.nextInt();
        int a = sc.nextInt();
        int b = sc.nextInt();
        for(int i = 1;i < 1000;i++){
            if(a<=k*i&&k*i<=b){
                System.out.println("OK");
                return;
            }
        }
        System.out.println("NG");
    }
    
}
