text: /**
   * Universidad de La Laguna
   * Escuela Superior de Ingeniería y Tecnología
   * Grado en Ingeniería Informática
   * Informática Básica
   *
   * @author Javier Garcia Santana || alu0101391663@ull.edu.es
   * @date Nov 19 2021
   * @brief The program prints yes if it finds an 'a' in the inserted sentence and otherwise it prints no
   * @see https://github.com/ULL-ESIT-IB-2021-2022/ib-2021-2022-P08-GitHub-Functions/blob/main/Functions-GitHub.md
   */
  
  #include <iostream>
  #include <vector>
  #include <string>
  
  using namespace std;
  
  /*
  This boolean function determines whether the character 'a' is present on a given string
  */
  bool AFinder(const string &kInput) {
    bool result = false;
    for (int i = 0; i < kInput.size(); ++i) {
      if (kInput[i] == 'a') {
        result = true;
      }
    }
    return result;
  }
  
  int main() {
    string input;
    getline(cin, input);
    if (input[input.size() - 1] == '.'){
      if (AFinder(input)) {
        cout << "yes" << endl;
      } else {
        cout << "no" << endl;
      }
    } else {
      cerr << "End-of-file reached or I/O error" << endl;
    }
    return 0;
  }