#include"bits/stdc++.h"
using namespace std;
#define REP(k,m,n) for(int (k)=(m);(k)<(n);(k)++)
#define rep(i,n) REP((i),0,(n))

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