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();
        sc.close();

        int tmp = K;
        int times = 1;
        boolean results = false;
        while (tmp <= B) {
            if (tmp <= B && tmp >= A) {
                results = true;
                break;
            }
            times++;
            tmp = times * K;
        }

        if (results) {
            System.out.println("OK");
        } else {
            System.out.println("NG");
        }
    }
} 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();
        sc.close();

        int tmp = K;
        int times = 1;
        boolean results = false;
        while (tmp <= B) {
            if (tmp <= B && tmp >= A) {
                results = true;
                break;
            }
            times++;
            tmp = times * K;
        }

        if (results) {
            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();
        sc.close();

        int tmp = K;
        int times = 1;
        boolean results = false;
        while (tmp <= B) {
            if (tmp <= B && tmp >= A) {
                results = true;
                break;
            }
            times++;
            tmp = times * K;
        }

        if (results) {
            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();
        sc.close();

        int tmp = K;
        int times = 1;
        boolean results = false;
        while (tmp <= B) {
            if (tmp <= B && tmp >= A) {
                results = true;
                break;
            }
            times++;
            tmp = times * K;
        }

        if (results) {
            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 sc.close() sc.close sc int tmp = K; tmp K int times = 1; times 1 boolean results = false; results false while (tmp <= B) {
            if (tmp <= B && tmp >= A) {
                results = true;
                break;
            }
            times++;
            tmp = times * K;
        } tmp <= B tmp B {
            if (tmp <= B && tmp >= A) {
                results = true;
                break;
            }
            times++;
            tmp = times * K;
        } if (tmp <= B && tmp >= A) {
                results = true;
                break;
            } tmp <= B && tmp >= A tmp <= B tmp B tmp >= A tmp A {
                results = true;
                break;
            } results = true results true break; times++ times tmp = times * K tmp times * K times K if (results) {
            System.out.println("OK");
        } else {
            System.out.println("NG");
        } results {
            System.out.println("OK");
        } System.out.println("OK") System.out.println System.out System System.out "OK" {
            System.out.println("NG");
        } 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();
        sc.close();

        int tmp = K;
        int times = 1;
        boolean results = false;
        while (tmp <= B) {
            if (tmp <= B && tmp >= A) {
                results = true;
                break;
            }
            times++;
            tmp = times * K;
        }

        if (results) {
            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();
        sc.close();

        int tmp = K;
        int times = 1;
        boolean results = false;
        while (tmp <= B) {
            if (tmp <= B && tmp >= A) {
                results = true;
                break;
            }
            times++;
            tmp = times * K;
        }

        if (results) {
            System.out.println("OK");
        } else {
            System.out.println("NG");
        }
    }
} Main
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();
        sc.close();

        int tmp = K;
        int times = 1;
        boolean results = false;
        while (tmp <= B) {
            if (tmp <= B && tmp >= A) {
                results = true;
                break;
            }
            times++;
            tmp = times * K;
        }

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