source_code: import java.io.BufferedReader;
  import static java.lang.Math.*;
  import java.io.File;
  import java.io.FileReader;
  import java.io.IOException;
  import java.io.InputStreamReader;
  import java.io.PrintWriter;
  import java.util.*;
  
  public class CFC23A implements Runnable {
  	BufferedReader in;
  	PrintWriter out;
  	StringTokenizer tok;
  
  	public static void main(String[] args) {
  		new Thread(new CFC23A()).start();
  	}
  
  	void solve() throws IOException {
  		int res = 0;
  		String str = nextToken();
  		for(int i = 0; i < str.length(); ++i)
  			for(int j = i + 1; j <= str.length(); ++j)
  				if(isOk(str.substring(i, j), str))
  					res = max(res, j - i);
  		out.println(res);
  	}
  
  	private boolean isOk(String substring, String str) {
  		int from = 0, kol = 0;
  		while(str.indexOf(substring, from) != -1 && kol < 2) {
  			++kol;
  			from = str.indexOf(substring, from) + 1;
  		}
  		return kol >= 2;
  	}
  
  	@Override
  	public void run() {
  		try {
  			in = new BufferedReader(new InputStreamReader(System.in));
  			// in = new BufferedReader(new FileReader(new File("input.txt")));
  			out = new PrintWriter(System.out);
  			//out = new PrintWriter(new File("output.txt"));
  			solve();
  			out.flush();
  			out.close();
  			in.close();
  		} catch (IOException e) {
  			// TODO Auto-generated catch block
  			e.printStackTrace();
  		}
  
  	}
  
  	String nextLine() throws IOException {
  		tok = null;
  		return in.readLine();
  	}
  
  	double nextDouble() throws IOException {
  		return Double.parseDouble(nextToken());
  	}
  
  	int nextInt() throws IOException {
  		return Integer.parseInt(nextToken());
  	}
  
  	String nextToken() throws IOException {
  		while (tok == null || !tok.hasMoreTokens()) {
  			tok = new StringTokenizer(in.readLine());
  		}
  		return tok.nextToken();
  	}
  }
  