#include <iostream>
#include <vector>
#include <map>
#include<string>
#define ll long long
using namespace std;
int main() {
    string s;
    bool f=0,g=0;
    getline(cin,s);
    for(int i=0;i<s.length();i++){
        if((i+1)%2==1){
            if(s[i]>='a' and s[i]<='z')
            {
                f=1;
            }
            else {
                f=0;
                break;
            }
        }
        else  {
            if(s[i]==' ') g=1;
            else{
                g=0;
                break;
            }
        }
        }
    if(f and g) cout<<"Yes"<<endl;
    else cout<<"No"<<endl;
     return 0;
}