#include <bits/stdc++.h>
using namespace std;
#define int long long
#define rep(i,n) for(int (i)=0;(i)<(n);(i)++)
#define rrep(i,n) for(int (i)=((n)-1);(i)>=0;(i)--)
#define itn int
#define all(x) (x).begin(),(x).end()
#define F first
#define S second
const long long INF = 1LL << 60;
const int MOD = 1000000007;
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; }
signed main(void){
    string s; getline(cin, s);
    
    rep(i,s.size()){
        if(i%2 == 0){
            if(! (s[i]>='a'&&s[i]<='z')) {cout<<"No"<<endl; return 0;}
        }else{
            if(s[i] != ' ') {cout<<"No"<<endl; return 0;}
        }
    }
    cout<<"Yes"<<endl;
}