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

int main() {
  ios::sync_with_stdio(false);

  string S;
  getline(cin, S);

  bool ng = false;
  for (int i = 0; i < S.size(); ++i) {
    if (i & 1) ng |= S[i] != ' ';
    else ng |= !islower(S[i]);
  }

  if (ng) cout << "No" << endl;
  else cout << "Yes" << endl;

  return 0;
}