#include <iostream>
#include <string>
using namespace std;

int main() {
  string S;
  getline(cin, S);
  for (int i = 1; i < S.size(); i += 2) {
    if (S[i] != ' ') {
      cout << "No" << endl;
      return 0;
    }
  }
  cout << "Yes" << endl;
}