/*** author: yuji9511 ***/
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<ll,ll> lpair;
const ll MOD = 1e9+7;
const ll INF = 1e18;
#define rep(i,m,n) for(ll i=(m);i<(n);i++)
#define rrep(i,m,n) for(ll i=(m);i>=(n);i--)
#define printa(x,n) for(ll i=0;i<n;i++){cout<<(x[i])<<" \n"[i==n-1];};
void print() {}
template <class H,class... T>
void print(H&& h, T&&... t){cout<<h<<" \n"[sizeof...(t)==0];print(forward<T>(t)...);}

int main(){
	cin.tie(0);
	ios::sync_with_stdio(false);
	string s;
	if (getline(cin, s)) {
		ll sz = s.size();
		bool ok = true;
		rep(i,0,sz){
			if(i % 2 == 0 && s[i] == ' '){
				ok = false;
			}else if(i % 2 == 1 && s[i] != ' '){
				ok = false;
			}
		}
		if(ok){
			print("Yes");
		}else{
			print("No");
		}
	}

	

}