#include <bits/stdc++.h>
#define rep(i, n) for(int i = 0; i < (int)n; i++)
using namespace std;
using ll = long long;

int main() {
    string s;
    getline(cin, s);
    int n = (int)s.size();
    bool utn = true;
    rep(i, n) {
        if(i % 2 && s[i] != ' ') utn = false;
        if(i % 2 == 0 && s[i] == ' ') utn = false;
    }
    if(utn) cout << "Yes" << endl;
    else cout << "No" << endl;
    return 0;
}