//Normal

#define _GLIBCXX_DEBUG
#define ll long long
#include <bits/stdc++.h>
using namespace std;
using Graph = vector<vector<int>>;

void print(auto a){
  cout << a;
}

void prints(auto a){
  cout << a << " ";
}

void prints(){
  cout << " ";
}

void printl(auto a){
  cout << a << endl;
}

void printl(){
  cout << endl;
}

void fix(int n){
  cout << fixed << setprecision(n);
}

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