import java.util.Scanner; // 偶串 public class EvenString { public static void main(String[] args) { Scanner input = new Scanner(System.in); String str = input.nextLine(); int len = str.length(); int result = 0; for(int i = 2;i<len;i+=2){ String substr = str.substring(0, len-i); if(isEvenString(substr)){ result = substr.length(); break; } } System.out.println(result); } public static boolean isEvenString(String str){ int len = str.length(); if(len%2==0){ int i=0,j=len/2; for(;i<len/2;i++){ if(str.charAt(i) == str.charAt(j)){ j++; }else{ return false; } } }else{ return false; } return true; } }