source_code: import java.util.*;
  import java.io.*;
  
  public class A
  {
      public static void main(String[] args)
      {
          Kattio io = new Kattio(System.in);
  
          int n = io.getInt();
          int ans = 0;
          int V = n;
          int A = n;
  
          A -= n/2;
          ans += n/2;
  
          V -= A;
          ans += A;
  
          A -= n/2;
          ans += n/2;
  
          io.println(ans);
          io.flush();
      }
  }
  
  
  class Kattio extends PrintWriter {
      public Kattio(InputStream i) {
  	super(new BufferedOutputStream(System.out));
  	r = new BufferedReader(new InputStreamReader(i));
      }
      public Kattio(InputStream i, OutputStream o) {
  	super(new BufferedOutputStream(o));
  	r = new BufferedReader(new InputStreamReader(i));
      }
  
      public boolean hasMoreTokens() {
  	return peekToken() != null;
      }
  
      public int getInt() {
  	return Integer.parseInt(nextToken());
      }
  
      public double getDouble() { 
  	return Double.parseDouble(nextToken());
      }
  
      public long getLong() {
  	return Long.parseLong(nextToken());
      }
  
      public String getWord() {
  	return nextToken();
      }
  
  
  
      private BufferedReader r;
      private String line;
      private StringTokenizer st;
      private String token;
  
      private String peekToken() {
  	if (token == null) 
  	    try {
  		while (st == null || !st.hasMoreTokens()) {
  		    line = r.readLine();
  		    if (line == null) return null;
  		    st = new StringTokenizer(line);
  		}
  		token = st.nextToken();
  	    } catch (IOException e) { }
  	return token;
      }
  
      private String nextToken() {
  	String ans = peekToken();
  	token = null;
  	return ans;
      }
  }
  