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

#define rep(i,n) for(ll i=0;i<(n);++i)
#define reps(i,n) for(ll i=1;i<=(n);++i)
using ll = long long;
using str = string;
constexpr long long INF = (1LL<<60);
constexpr long long MOD = (1e9+7);
template<class T>inline bool chmax(T &a,const T &b){if(a<b){a=b;return true;}return false;}
template<class T>inline bool chmin(T &a,const T &b){if(a>b){a=b;return true;}return false;}
inline void dump(){cout<<endl;}
template<class Head,class... Tail>inline void dump(Head&& head, Tail&&... tail){cout<<head<<", ";dump(forward<Tail>(tail)...);}
template<typename T>inline istream &operator>>(istream&input,vector<T>&v){for(auto &elemnt:v)input>>elemnt;return input;}
template<class T>vector<T> make_vector(size_t a){return vector<T>(a);}
template<class T, class... Ts>auto make_vector(size_t a, Ts... ts){return vector<decltype(make_vector<T>(ts...))>(a, make_vector<T>(ts...));}

main(){
  //cin.tie(0);
  //ios::sync_with_stdio(0);
  //cout<<fixed<<setprecision(10);

  string s;
  getline(cin,s);
  ll n=s.size();
  rep(i,n){
    if(i&1){
      if(s[i]!=' '){
        puts("No");
        exit(0);
      }
    }
    else{
      if('a'<=s[i]&&s[i]<='z'){

      }
      else{
        puts("No");
        exit(0);
      }
    }
  }

  puts("Yes");

}