#include <unordered_map>
#include <functional>
#include <algorithm>
#include <iostream>
#include <complex>
#include <cstring>
#include <string>
#include <vector>
#include <queue>
#include <tuple>
#include <set>
#include <map>

#define FOR0(var, max) for (ul (var) = 0; (var) < (max); ++(var))
#define FORi(var, min, max) for (ul (var) = (min); (var) < (max); ++(var))
#define FORi_INV(var, min, max) for (ul (var) = (max) - 1; (var) + 1 > (min); --(var))
#define FORITER(var, iter) for (auto (iter) = (var).begin(); (iter) != (var).end(); (iter)++)
#define FORITER_INV(var, iter) for (auto (iter) = (var).rbegin(); (iter) != (var).rend(); (iter)++)

#define LTLT(a, b, c) (((a) < (b)) && ((b) < (c)))
#define LELT(a, b, c) (((a) <= (b)) && ((b) < (c)))
#define LTLE(a, b, c) (((a) < (b)) && ((b) <= (c)))
#define LELE(a, b, c) (((a) <= (b)) && ((b) <= (c)))

using namespace std;

using uc = unsigned char;
using ui = unsigned int;
using ul = unsigned long long int;

using sc = signed char;
using si = signed int;
using sl = signed long long int;


const static ui NMAX = 100;
static ui N;
static sc S[NMAX];

void solve(void) {
  FOR0(i, N) {
    if (((i % 2) == 0 && !LELE('a', S[i], 'z')) || ((i % 2) == 1 && S[i] != ' ')) {
      cout << "No" << endl;
      return;
    }
  }
  cout << "Yes" << endl;
}

int main(void) {
  sc c;
  N = 0;
  while (1) {
    scanf("%c", &c);
    if (c == '\n') {
      break;
    }
    S[N] = c;
    N++;
  }
  solve();
  return 0;
}