source_code: import java.util.HashSet;
  import java.util.Scanner;
  import java.util.Set;
  
  
  public class R023A {
  	String str;
  	int n; 
  	public R023A() {
  		Scanner scanner = new Scanner(System.in);
  		str = scanner.next();
  		n = str.length();
  	}
  
  	private void process() {
  		int length = -1;
  		for(int i=1; i<n; i++) {
  			Set<String> set = new HashSet<String>();
  			length = n - i;
  			for(int j=0; j<=i; j++) {
  				String sub = str.substring(j, j+length);
  				set.add(sub);
  			}
  			if(set.size() < i+1) {
  				System.out.println(length);
  				return;
  			}
  		}
  		System.out.println(0);
  	}
  
  	public static void main(String[] args) {
  		new R023A().process();
  	}
  }
  