import java.util.*;
 
class A_YoureGivenAString {
	public static void main(String[] args) throws Exception{
		String str = new Scanner(System.in).next();
		Set<String> set = new HashSet<String>();
		String max = "";
		for(int l = 1; l < str.length(); ++l){
			for(int i = 0; i < str.length()-l; ++i){
				String substr = str.substring(i, i+l);
				if(!set.contains(substr) && str.indexOf(substr) != str.lastIndexOf(substr)){
					set.add(substr);
					if(substr.length() > max.length()){
						max = substr;
					}
				}
			}
		}
		System.out.println(max.length());
	}
 
}
 

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

YWJjZAo=

abcd