#include <cmath>
#include <iostream>
#include <string>

int main() {
  std::string s;
  std::getline(std::cin, s);
  bool ok = true;
  for (int i = 0; i < s.size(); i += 2) {
    ok &= 0 <= s[i] - 'a' && s[i] - 'a' < 26;
  }
  for (int i = 1; i< s.size(); i += 2) {
    ok &= s[i] == ' ';
  }
  std::cout << (ok ? "Yes" : "No") << std::endl;
}