import java.io.*;
import java.util.*;
public class Main {
static PrintWriter pw =new PrintWriter(new OutputStreamWriter(System.out));
    public static void main(String[] args) {
	// write your code here
        MyScanner mc = new MyScanner();
        boolean game= false;
        int K = mc.nextInt(); int A = mc.nextInt(); int B = mc.nextInt();
        int count =0;
        while (count<=1000){
            if (count>=A&&count<=B){
                game = true;
            }
            count+=K;
        }
        if (count>=A&&count<=B){
            game = true;
        }
        pw.println(game?"OK":"NG");
        pw.flush();
    }

public static class MyScanner {
      BufferedReader br;
      StringTokenizer st;

      public MyScanner() {
         br = new BufferedReader(new InputStreamReader(System.in));
      }

      String next() {
          while (st == null || !st.hasMoreElements()) {
              try {
                  st = new StringTokenizer(br.readLine());
              } catch (IOException e) {
                  e.printStackTrace();
              }
          }
          return st.nextToken();
      }

      int nextInt() {
          return Integer.parseInt(next());
      }

      long nextLong() {
          return Long.parseLong(next());
      }

      double nextDouble() {
          return Double.parseDouble(next());
      }

      String nextLine(){
          String str = "";
	  try {
	     str = br.readLine();
	  } catch (IOException e) {
	     e.printStackTrace();
	  }
	  return str;
      }

   }

} import java.io.*; io.* java import java.util.*; util.* java public class Main {
static PrintWriter pw =new PrintWriter(new OutputStreamWriter(System.out));
    public static void main(String[] args) {
	// write your code here
        MyScanner mc = new MyScanner();
        boolean game= false;
        int K = mc.nextInt(); int A = mc.nextInt(); int B = mc.nextInt();
        int count =0;
        while (count<=1000){
            if (count>=A&&count<=B){
                game = true;
            }
            count+=K;
        }
        if (count>=A&&count<=B){
            game = true;
        }
        pw.println(game?"OK":"NG");
        pw.flush();
    }

public static class MyScanner {
      BufferedReader br;
      StringTokenizer st;

      public MyScanner() {
         br = new BufferedReader(new InputStreamReader(System.in));
      }

      String next() {
          while (st == null || !st.hasMoreElements()) {
              try {
                  st = new StringTokenizer(br.readLine());
              } catch (IOException e) {
                  e.printStackTrace();
              }
          }
          return st.nextToken();
      }

      int nextInt() {
          return Integer.parseInt(next());
      }

      long nextLong() {
          return Long.parseLong(next());
      }

      double nextDouble() {
          return Double.parseDouble(next());
      }

      String nextLine(){
          String str = "";
	  try {
	     str = br.readLine();
	  } catch (IOException e) {
	     e.printStackTrace();
	  }
	  return str;
      }

   }

} Main static PrintWriter pw =new PrintWriter(new OutputStreamWriter(System.out)); pw new PrintWriter(new OutputStreamWriter(System.out)) public static void main(String[] args) {
	// write your code here
        MyScanner mc = new MyScanner();
        boolean game= false;
        int K = mc.nextInt(); int A = mc.nextInt(); int B = mc.nextInt();
        int count =0;
        while (count<=1000){
            if (count>=A&&count<=B){
                game = true;
            }
            count+=K;
        }
        if (count>=A&&count<=B){
            game = true;
        }
        pw.println(game?"OK":"NG");
        pw.flush();
    } main {
	// write your code here
        MyScanner mc = new MyScanner();
        boolean game= false;
        int K = mc.nextInt(); int A = mc.nextInt(); int B = mc.nextInt();
        int count =0;
        while (count<=1000){
            if (count>=A&&count<=B){
                game = true;
            }
            count+=K;
        }
        if (count>=A&&count<=B){
            game = true;
        }
        pw.println(game?"OK":"NG");
        pw.flush();
    } MyScanner mc = new MyScanner(); mc new MyScanner() boolean game= false; game false int K = mc.nextInt(); K mc.nextInt() mc.nextInt mc int A = mc.nextInt(); A mc.nextInt() mc.nextInt mc int B = mc.nextInt(); B mc.nextInt() mc.nextInt mc int count =0; count 0 while (count<=1000){
            if (count>=A&&count<=B){
                game = true;
            }
            count+=K;
        } count<=1000 count 1000 {
            if (count>=A&&count<=B){
                game = true;
            }
            count+=K;
        } if (count>=A&&count<=B){
                game = true;
            } count>=A&&count<=B count>=A count A count<=B count B {
                game = true;
            } game = true game true count+=K count K if (count>=A&&count<=B){
            game = true;
        } count>=A&&count<=B count>=A count A count<=B count B {
            game = true;
        } game = true game true pw.println(game?"OK":"NG") pw.println pw game?"OK":"NG" game "OK" "NG" pw.flush() pw.flush pw String[] args args public static class MyScanner {
      BufferedReader br;
      StringTokenizer st;

      public MyScanner() {
         br = new BufferedReader(new InputStreamReader(System.in));
      }

      String next() {
          while (st == null || !st.hasMoreElements()) {
              try {
                  st = new StringTokenizer(br.readLine());
              } catch (IOException e) {
                  e.printStackTrace();
              }
          }
          return st.nextToken();
      }

      int nextInt() {
          return Integer.parseInt(next());
      }

      long nextLong() {
          return Long.parseLong(next());
      }

      double nextDouble() {
          return Double.parseDouble(next());
      }

      String nextLine(){
          String str = "";
	  try {
	     str = br.readLine();
	  } catch (IOException e) {
	     e.printStackTrace();
	  }
	  return str;
      }

   } MyScanner BufferedReader br; br StringTokenizer st; st public MyScanner() {
         br = new BufferedReader(new InputStreamReader(System.in));
      } MyScanner {
         br = new BufferedReader(new InputStreamReader(System.in));
      } br = new BufferedReader(new InputStreamReader(System.in)) br new BufferedReader(new InputStreamReader(System.in)) String next() {
          while (st == null || !st.hasMoreElements()) {
              try {
                  st = new StringTokenizer(br.readLine());
              } catch (IOException e) {
                  e.printStackTrace();
              }
          }
          return st.nextToken();
      } next {
          while (st == null || !st.hasMoreElements()) {
              try {
                  st = new StringTokenizer(br.readLine());
              } catch (IOException e) {
                  e.printStackTrace();
              }
          }
          return st.nextToken();
      } while (st == null || !st.hasMoreElements()) {
              try {
                  st = new StringTokenizer(br.readLine());
              } catch (IOException e) {
                  e.printStackTrace();
              }
          } st == null || !st.hasMoreElements() st == null st null !st.hasMoreElements() st.hasMoreElements() st.hasMoreElements st {
              try {
                  st = new StringTokenizer(br.readLine());
              } catch (IOException e) {
                  e.printStackTrace();
              }
          } try {
                  st = new StringTokenizer(br.readLine());
              } catch (IOException e) {
                  e.printStackTrace();
              } catch (IOException e) {
                  e.printStackTrace();
              } IOException e {
                  e.printStackTrace();
              } e.printStackTrace() e.printStackTrace e {
                  st = new StringTokenizer(br.readLine());
              } st = new StringTokenizer(br.readLine()) st new StringTokenizer(br.readLine()) return st.nextToken(); st.nextToken() st.nextToken st int nextInt() {
          return Integer.parseInt(next());
      } nextInt {
          return Integer.parseInt(next());
      } return Integer.parseInt(next()); Integer.parseInt(next()) Integer.parseInt Integer next() next long nextLong() {
          return Long.parseLong(next());
      } nextLong {
          return Long.parseLong(next());
      } return Long.parseLong(next()); Long.parseLong(next()) Long.parseLong Long next() next double nextDouble() {
          return Double.parseDouble(next());
      } nextDouble {
          return Double.parseDouble(next());
      } return Double.parseDouble(next()); Double.parseDouble(next()) Double.parseDouble Double next() next String nextLine(){
          String str = "";
	  try {
	     str = br.readLine();
	  } catch (IOException e) {
	     e.printStackTrace();
	  }
	  return str;
      } nextLine {
          String str = "";
	  try {
	     str = br.readLine();
	  } catch (IOException e) {
	     e.printStackTrace();
	  }
	  return str;
      } String str = ""; str "" try {
	     str = br.readLine();
	  } catch (IOException e) {
	     e.printStackTrace();
	  } catch (IOException e) {
	     e.printStackTrace();
	  } IOException e {
	     e.printStackTrace();
	  } e.printStackTrace() e.printStackTrace e {
	     str = br.readLine();
	  } str = br.readLine() str br.readLine() br.readLine br return str; str public class Main {
static PrintWriter pw =new PrintWriter(new OutputStreamWriter(System.out));
    public static void main(String[] args) {
	// write your code here
        MyScanner mc = new MyScanner();
        boolean game= false;
        int K = mc.nextInt(); int A = mc.nextInt(); int B = mc.nextInt();
        int count =0;
        while (count<=1000){
            if (count>=A&&count<=B){
                game = true;
            }
            count+=K;
        }
        if (count>=A&&count<=B){
            game = true;
        }
        pw.println(game?"OK":"NG");
        pw.flush();
    }

public static class MyScanner {
      BufferedReader br;
      StringTokenizer st;

      public MyScanner() {
         br = new BufferedReader(new InputStreamReader(System.in));
      }

      String next() {
          while (st == null || !st.hasMoreElements()) {
              try {
                  st = new StringTokenizer(br.readLine());
              } catch (IOException e) {
                  e.printStackTrace();
              }
          }
          return st.nextToken();
      }

      int nextInt() {
          return Integer.parseInt(next());
      }

      long nextLong() {
          return Long.parseLong(next());
      }

      double nextDouble() {
          return Double.parseDouble(next());
      }

      String nextLine(){
          String str = "";
	  try {
	     str = br.readLine();
	  } catch (IOException e) {
	     e.printStackTrace();
	  }
	  return str;
      }

   }

} public class Main {
static PrintWriter pw =new PrintWriter(new OutputStreamWriter(System.out));
    public static void main(String[] args) {
	// write your code here
        MyScanner mc = new MyScanner();
        boolean game= false;
        int K = mc.nextInt(); int A = mc.nextInt(); int B = mc.nextInt();
        int count =0;
        while (count<=1000){
            if (count>=A&&count<=B){
                game = true;
            }
            count+=K;
        }
        if (count>=A&&count<=B){
            game = true;
        }
        pw.println(game?"OK":"NG");
        pw.flush();
    }

public static class MyScanner {
      BufferedReader br;
      StringTokenizer st;

      public MyScanner() {
         br = new BufferedReader(new InputStreamReader(System.in));
      }

      String next() {
          while (st == null || !st.hasMoreElements()) {
              try {
                  st = new StringTokenizer(br.readLine());
              } catch (IOException e) {
                  e.printStackTrace();
              }
          }
          return st.nextToken();
      }

      int nextInt() {
          return Integer.parseInt(next());
      }

      long nextLong() {
          return Long.parseLong(next());
      }

      double nextDouble() {
          return Double.parseDouble(next());
      }

      String nextLine(){
          String str = "";
	  try {
	     str = br.readLine();
	  } catch (IOException e) {
	     e.printStackTrace();
	  }
	  return str;
      }

   }

} Main
import java.io.*;
import java.util.*;
public class Main {
static PrintWriter pw =new PrintWriter(new OutputStreamWriter(System.out));
    public static void main(String[] args) {
	// write your code here
        MyScanner mc = new MyScanner();
        boolean game= false;
        int K = mc.nextInt(); int A = mc.nextInt(); int B = mc.nextInt();
        int count =0;
        while (count<=1000){
            if (count>=A&&count<=B){
                game = true;
            }
            count+=K;
        }
        if (count>=A&&count<=B){
            game = true;
        }
        pw.println(game?"OK":"NG");
        pw.flush();
    }

public static class MyScanner {
      BufferedReader br;
      StringTokenizer st;

      public MyScanner() {
         br = new BufferedReader(new InputStreamReader(System.in));
      }

      String next() {
          while (st == null || !st.hasMoreElements()) {
              try {
                  st = new StringTokenizer(br.readLine());
              } catch (IOException e) {
                  e.printStackTrace();
              }
          }
          return st.nextToken();
      }

      int nextInt() {
          return Integer.parseInt(next());
      }

      long nextLong() {
          return Long.parseLong(next());
      }

      double nextDouble() {
          return Double.parseDouble(next());
      }

      String nextLine(){
          String str = "";
	  try {
	     str = br.readLine();
	  } catch (IOException e) {
	     e.printStackTrace();
	  }
	  return str;
      }

   }

}
