#include <bits/stdc++.h>
using namespace std;
using i64 = long long;
#define rep(i,s,e) for(i64 (i) = (s);(i) < (e);(i)++)
#define all(x) x.begin(),x.end()
#define let auto const

template<typename... Types>
struct dynarr: std::vector<Types...> {
  using std::vector<Types...>::vector;
  using size_type = typename std::vector<Types...>::size_type;
  auto&& operator[](size_type i) { return this->at(i); }
  auto&& operator[](size_type i) const { return this->at(i); }
};

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