Envío 2060

Código

#include <iostream>
#include <string>

using namespace std;

bool endsWith(string const &str, string const &ending) {
    if (str.length() >= ending.length()) {
        return str.compare(
				 str.length() - ending.length(),
				 ending.length(),
				 ending) == 0;
    } else {
        return false;
    }
}

int main() {
  string input;
  cin >> input;
  int max_border = 0;
  for (int i = 1; i < input.length(); i++) {
	 string border = input.substr(0, i);
	 if(endsWith(input, border)) {
		max_border = border.length();
	 }
  }
  cout << max_border << endl;
  return 0;
}