#include <bits/stdc++.h>

using namespace std;
using ll = long long;

const int MOD = 1e9+7;

int main()
{
    string s;
    getline(cin, s);
    for(int i = 0;i < s.size();i++){
        if(i % 2 == 0 && s[i] == ' '){
            cout<<"No"<<endl;
            return 0;
        }
        if(i % 2 == 1 && s[i] != ' '){
            cout<<"No"<<endl;
            return 0;
        }
    }
    cout<<"Yes"<<endl;
}