import java.util.*;

public class Main {
  public static void main(String[] args) {
    Scanner s = new Scanner(System.in);
        final int k = s.nextInt();
        int a = s.nextInt();
        final int b = s.nextInt();

        boolean okFlg = false;
        while (a <= b) {
            if (a % k == 0) {
                okFlg = true;
                break;
            }
            a++;
        }
        if (okFlg) {
            System.out.println("OK");
        } else {
            System.out.println("NG");
        }
  }
} import java.util.*; util.* java public class Main {
  public static void main(String[] args) {
    Scanner s = new Scanner(System.in);
        final int k = s.nextInt();
        int a = s.nextInt();
        final int b = s.nextInt();

        boolean okFlg = false;
        while (a <= b) {
            if (a % k == 0) {
                okFlg = true;
                break;
            }
            a++;
        }
        if (okFlg) {
            System.out.println("OK");
        } else {
            System.out.println("NG");
        }
  }
} Main public static void main(String[] args) {
    Scanner s = new Scanner(System.in);
        final int k = s.nextInt();
        int a = s.nextInt();
        final int b = s.nextInt();

        boolean okFlg = false;
        while (a <= b) {
            if (a % k == 0) {
                okFlg = true;
                break;
            }
            a++;
        }
        if (okFlg) {
            System.out.println("OK");
        } else {
            System.out.println("NG");
        }
  } main {
    Scanner s = new Scanner(System.in);
        final int k = s.nextInt();
        int a = s.nextInt();
        final int b = s.nextInt();

        boolean okFlg = false;
        while (a <= b) {
            if (a % k == 0) {
                okFlg = true;
                break;
            }
            a++;
        }
        if (okFlg) {
            System.out.println("OK");
        } else {
            System.out.println("NG");
        }
  } Scanner s = new Scanner(System.in); s new Scanner(System.in) final int k = s.nextInt(); k s.nextInt() s.nextInt s int a = s.nextInt(); a s.nextInt() s.nextInt s final int b = s.nextInt(); b s.nextInt() s.nextInt s boolean okFlg = false; okFlg false while (a <= b) {
            if (a % k == 0) {
                okFlg = true;
                break;
            }
            a++;
        } a <= b a b {
            if (a % k == 0) {
                okFlg = true;
                break;
            }
            a++;
        } if (a % k == 0) {
                okFlg = true;
                break;
            } a % k == 0 a % k a k 0 {
                okFlg = true;
                break;
            } okFlg = true okFlg true break; a++ a if (okFlg) {
            System.out.println("OK");
        } else {
            System.out.println("NG");
        } okFlg {
            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 s = new Scanner(System.in);
        final int k = s.nextInt();
        int a = s.nextInt();
        final int b = s.nextInt();

        boolean okFlg = false;
        while (a <= b) {
            if (a % k == 0) {
                okFlg = true;
                break;
            }
            a++;
        }
        if (okFlg) {
            System.out.println("OK");
        } else {
            System.out.println("NG");
        }
  }
} public class Main {
  public static void main(String[] args) {
    Scanner s = new Scanner(System.in);
        final int k = s.nextInt();
        int a = s.nextInt();
        final int b = s.nextInt();

        boolean okFlg = false;
        while (a <= b) {
            if (a % k == 0) {
                okFlg = true;
                break;
            }
            a++;
        }
        if (okFlg) {
            System.out.println("OK");
        } else {
            System.out.println("NG");
        }
  }
} Main
import java.util.*;

public class Main {
  public static void main(String[] args) {
    Scanner s = new Scanner(System.in);
        final int k = s.nextInt();
        int a = s.nextInt();
        final int b = s.nextInt();

        boolean okFlg = false;
        while (a <= b) {
            if (a % k == 0) {
                okFlg = true;
                break;
            }
            a++;
        }
        if (okFlg) {
            System.out.println("OK");
        } else {
            System.out.println("NG");
        }
  }
}