#include <bits/stdc++.h>
using namespace std::literals::string_literals;
using i64 = std::int_fast64_t;
using std::cout;
using std::endl;
using std::cin;

template<typename T>
std::vector<T> make_v(size_t a){return std::vector<T>(a);}

template<typename T,typename... Ts>
auto make_v(size_t a,Ts... ts){
  return std::vector<decltype(make_v<T>(ts...))>(a,make_v<T>(ts...));
}

int main() {
	std::string s; getline(cin, s);
	
	for(int i = 0; i < s.size(); i += 2) {
		if(s[i] == ' ' or (i + 1 < s.size() and s[i + 1] != ' ')) {
			printf("No\n");
			return 0;
		}
	}
	printf("Yes\n");
	return 0;
}