#include <bits/stdc++.h>

using namespace std;

int main() {
  string s;
  cin >> s;

  for (int i = 0; i < s.size(); i++) {
    if ((i + 1) % 2) {
      if (s[i] == ' ') {
        cout << "No\n";
        return 0;
      }
    } else {
      if (s[i] != ' ') {
        cout << "No\n";
        return 0;
      }
    }
  }
  cout << "Yes\n";

  return 0;
}