#define _GLIBCXX_DEBUG
#include <bits/stdc++.h>
using namespace std;

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