import java.util.*;

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();

    int count = 0;

    boolean flg = true;

    while(flg) {
      count += k;

      if(a <= count && count <= b) {
        flg = true;
        break;
      }

      if(count > b) {
        flg = false;
        break;
      }
    }

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

    sc.close();
  }
} import java.util.*; util.* java 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();

    int count = 0;

    boolean flg = true;

    while(flg) {
      count += k;

      if(a <= count && count <= b) {
        flg = true;
        break;
      }

      if(count > b) {
        flg = false;
        break;
      }
    }

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

    sc.close();
  }
} 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();

    int count = 0;

    boolean flg = true;

    while(flg) {
      count += k;

      if(a <= count && count <= b) {
        flg = true;
        break;
      }

      if(count > b) {
        flg = false;
        break;
      }
    }

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

    sc.close();
  } main {
    Scanner sc = new Scanner(System.in);
    int k = sc.nextInt();
    int a = sc.nextInt();
    int b = sc.nextInt();

    int count = 0;

    boolean flg = true;

    while(flg) {
      count += k;

      if(a <= count && count <= b) {
        flg = true;
        break;
      }

      if(count > b) {
        flg = false;
        break;
      }
    }

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

    sc.close();
  } 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 count = 0; count 0 boolean flg = true; flg true while(flg) {
      count += k;

      if(a <= count && count <= b) {
        flg = true;
        break;
      }

      if(count > b) {
        flg = false;
        break;
      }
    } flg {
      count += k;

      if(a <= count && count <= b) {
        flg = true;
        break;
      }

      if(count > b) {
        flg = false;
        break;
      }
    } count += k count k if(a <= count && count <= b) {
        flg = true;
        break;
      } a <= count && count <= b a <= count a count count <= b count b {
        flg = true;
        break;
      } flg = true flg true break; if(count > b) {
        flg = false;
        break;
      } count > b count b {
        flg = false;
        break;
      } flg = false flg false break; if(flg) {
      System.out.println("OK");
    } else {
      System.out.println("NG");
    } flg {
      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" sc.close() sc.close sc String[] args args
import java.util.*;

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();

    int count = 0;

    boolean flg = true;

    while(flg) {
      count += k;

      if(a <= count && count <= b) {
        flg = true;
        break;
      }

      if(count > b) {
        flg = false;
        break;
      }
    }

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

    sc.close();
  }
}