#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < n; ++i)
using ll = long long;
using namespace std;
const int INF = 1e9;

int main() {
    string S;
    int cnt = 0;
    bool flag = true;

    getline(cin, S);
    rep(i,S.size()) {
        if (cnt % 2 == 0 && S[i] == ' ')
            flag = false;
        else if (cnt % 2 == 1 && S[i] != ' ')
            flag = false;
        cnt++;
    }

    flag ? cout << "Yes" : cout << "No";
    cout << endl;

    return 0;
}