#include<iostream>
#include<string>
#include <vector>
#include<queue>
#include<map>
#include<algorithm>
#include<iomanip>
#include<cmath>
#include<bitset>
using namespace std;
using vi = vector<int>;
using vii = vector<vi>;
using vs = vector<string>;
using pii = pair<int, int>;
#define rep(i,n) for(int i=0;i<n;i++)
#define rep2(i,m,n) for(int i=m;i<n;i++)
#define vsort(v) sort(v.begin(), v.end())
#define rv(v) reverse(v.begin(), v.end())
#define ll long long
using vll = vector<ll>;
using Graph = vii;
const ll MOD = 1e9 + 7;

int main() {
	string s;
	cin >> s;
	bool b1 = true, b2 = true;
	for (int i = 1; i < s.size(); i += 2) {
		if (s[i] != ' ') {
			b1 = false;
			break;
		}
	}
	for (int i = 1; i < s.size(); i += 2) {
		if (!('a' <= s[i] && s[i] <= 'z')) {
			b2 = false;
			break;
		}
	}

	if (b1 && b2) cout << "Yes" << endl;
	else cout << "No" << endl;
}