#include <bits/stdc++.h>
using namespace std;

bool solve() {
	string s; getline(cin, s);
	int n = s.size();
	for(int i = 0; i < n; ++i) {
		char c = s[i];
		if(i % 2 == 0) {
			if('a' <= c and c <= 'z') continue;
			return false;
		} else {
			if(c != ' ' and c != 13) return false;
		}
	}
	return true;
}

int main() {
	cout << (solve() ? "Yes" : "No") << endl;
	return 0;
}