#include<bits/stdc++.h>
#define int long long
using namespace std;
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (a>b) { a=b; return 1; } return 0; }

signed main()
{
    cin.tie(0);
    ios::sync_with_stdio(false);

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