#include <bits/stdc++.h>
#define rep(i,n)for(long long i=0;i<(n);i++)
using namespace std;
typedef unsigned long long ull;
typedef long long ll;
const ll INF=1e18;
const int MOD=1e9+7;
const double pi=acos(-1);

int main(){
  string s;
  getline(cin,s);
  bool ok=true;
  rep(i,s.size()){
    if(i%2==0 &&('a'>s[i] || s[i]>'z'))ok=false;
    if(i%2==1 && s[i]!=' ')ok=false;
  }
  if(ok)cout<<"Yes"<<endl;   
  else cout<<"No"<<endl;
}