import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int K = sc.nextInt(), A = sc.nextInt(), B = sc.nextInt();
        if(B - A >= K) {
            System.out.print("OK");
            return;
        }

        for(int i = A; i < B + 1; i++) {
            if(i % K == 0) {
                System.out.print("OK");
                return;
            }
        }
        System.out.print("NG");
    }
} import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int K = sc.nextInt(), A = sc.nextInt(), B = sc.nextInt();
        if(B - A >= K) {
            System.out.print("OK");
            return;
        }

        for(int i = A; i < B + 1; i++) {
            if(i % K == 0) {
                System.out.print("OK");
                return;
            }
        }
        System.out.print("NG");
    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int K = sc.nextInt(), A = sc.nextInt(), B = sc.nextInt();
        if(B - A >= K) {
            System.out.print("OK");
            return;
        }

        for(int i = A; i < B + 1; i++) {
            if(i % K == 0) {
                System.out.print("OK");
                return;
            }
        }
        System.out.print("NG");
    } main {
        Scanner sc = new Scanner(System.in);
        int K = sc.nextInt(), A = sc.nextInt(), B = sc.nextInt();
        if(B - A >= K) {
            System.out.print("OK");
            return;
        }

        for(int i = A; i < B + 1; i++) {
            if(i % K == 0) {
                System.out.print("OK");
                return;
            }
        }
        System.out.print("NG");
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int K = sc.nextInt() K sc.nextInt() sc.nextInt sc A = sc.nextInt() A sc.nextInt() sc.nextInt sc B = sc.nextInt(); B sc.nextInt() sc.nextInt sc if(B - A >= K) {
            System.out.print("OK");
            return;
        } B - A >= K B - A B A K {
            System.out.print("OK");
            return;
        } System.out.print("OK") System.out.print System.out System System.out "OK" return; for(int i = A; i < B + 1; i++) {
            if(i % K == 0) {
                System.out.print("OK");
                return;
            }
        } int i = A; int i = A; i A i < B + 1 i B + 1 B 1 i++ i++ i {
            if(i % K == 0) {
                System.out.print("OK");
                return;
            }
        } {
            if(i % K == 0) {
                System.out.print("OK");
                return;
            }
        } if(i % K == 0) {
                System.out.print("OK");
                return;
            } i % K == 0 i % K i K 0 {
                System.out.print("OK");
                return;
            } System.out.print("OK") System.out.print System.out System System.out "OK" return; System.out.print("NG") System.out.print 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(), A = sc.nextInt(), B = sc.nextInt();
        if(B - A >= K) {
            System.out.print("OK");
            return;
        }

        for(int i = A; i < B + 1; i++) {
            if(i % K == 0) {
                System.out.print("OK");
                return;
            }
        }
        System.out.print("NG");
    }
} public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int K = sc.nextInt(), A = sc.nextInt(), B = sc.nextInt();
        if(B - A >= K) {
            System.out.print("OK");
            return;
        }

        for(int i = A; i < B + 1; i++) {
            if(i % K == 0) {
                System.out.print("OK");
                return;
            }
        }
        System.out.print("NG");
    }
} Main
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int K = sc.nextInt(), A = sc.nextInt(), B = sc.nextInt();
        if(B - A >= K) {
            System.out.print("OK");
            return;
        }

        for(int i = A; i < B + 1; i++) {
            if(i % K == 0) {
                System.out.print("OK");
                return;
            }
        }
        System.out.print("NG");
    }
}
