#include <fstream>
#include <iostream>
#include <utility> //pair
#include <string>
#include <cmath> //pow


int main() {

	//std::ifstream inf("Text.txt");	std::cin.rdbuf(inf.rdbuf());

	std::string S;
	std::getline(std::cin, S);

	bool flg = true;

	for (unsigned int i = 0; i < S.length(); i++) {
		if (i % 2 == 0) {
			if (S[i] == ' ') {
				flg = false;
				break;
			}
		}
		else {
			if (S[i] != ' ') {
				flg = false;
				break;
			}
		}
	}

	if (flg) {
		std::cout << "Yes" << std::endl;
	}
	else {
		std::cout << "No" << std::endl;
	}

}