#include <iostream>
using namespace std;
int main(){
    string str;
    getline(cin,str);
    bool judge=true;
    for(int i=0;i<str.size();i++){
        if(i%2==0){
            if(str[i]<'a' || 'z'<str[i])judge=false;
        }else{
            if(str[i]!=' ')judge=false;
        }
    }
    if(judge)cout << "Yes" << endl;
    else cout << "No" << endl;
    return 0;
}