#include <iostream>
#include <string>
using namespace std;
int main(){
	string S;
	getline(cin, S);
	int N = S.size();
	bool ok = true;
	for (int i = 0; i < N; i++){
		if (i % 2 == 0 && S[i] == ' '){
			ok = false;
		}
		if (i % 2 == 1 && S[i] != ' '){
			ok = false;
		}
	}
	if (ok){
		cout << "Yes" << endl;
	} else {
		cout << "No" << endl;
	}
}