#include <bits/stdc++.h>
using namespace std;
#include <atcoder/all>
using namespace atcoder;

#define ll long long
#define rep(i, n) for (int i = 0; i < (n); i++)
#define P pair<int, int>
#define LP pair<ll, ll>


int main() {
  string s;
  cin >> s;
  rep(i,s.size()) {
    if (i%2==0 && !(s[i]-'a' >= 0 && s[i]-'a' <= 25)) {
      cout << "No" << endl;
      return 0;
    }
    if (i%2==1 && s[i]!= ' ') {
      cout << "No" << endl;
      return 0;
    }
    

  }
  cout << "Yes" << endl;

  
}