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

typedef signed long long ll;
typedef long double ld;

#define rep(i,n) for(int i = 0; i < (n); i++)
#define all(x) x.begin(),x.end()

#define DEBUG

int main()
{
	string s;
	getline(cin, s);

	bool ans = true;
	rep(i, s.size())
	{
		if(i % 2 == 0)
		{
			if(s[i] == ' ') ans = false;
		}
		if(i % 2 == 1)
		{
			if(s[i] != ' ') ans = false;
		}
	}

	if(ans)
	{
		cout << "Yes" << endl;
	}
	else
	{
		cout << "No" << endl;
	}

	return 0;
}