#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); ++i)
using ll = long long;
using P = pair<int,int>;
static const int mod1 = 998244353;
static const int mod2 = 1000000007;

int main() {
  string s;
  cin >> s;
  int size=s.size();
  rep(i,size) {
    if(i%2==0) {
      if('a'<=s[i] && s[i]<='z') continue;
      else {
        cout << "No" << endl;
        return 0;
      }
    }
    if(i%2==1) {
      if('A'<=s[i] && s[i]<='Z') continue;
      else {
        cout << "No" << endl;
        return 0;
      }
    }
  }
  cout << "Yes" << endl;
}
  

#include <bits/stdc++.h>
#include <cassert>
#define rep(i, N) for (int i = 0; i < (N); ++i)
#define rep2(i, a, b) for (ll i = a; i <= b; ++i)
#define rep3(i, a, b) for (ll i = a; i >= b; --i)
#define pb push_back
#define eb emplace_back
#define fi first
#define se second
#define all(c) begin(c), end(c)
#define ok() puts(ok ? "Yes" : "No");
template <class T> bool chmax(T &a, const T &b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
template <class T> bool chmin(T &a, const T &b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
using namespace std;
using ll = long long;
using vi = vector<int>;
using vll = vector<ll>;
using ii = pair<int, int>;
using vvi = vector<vi>;
using vii = vector<ii>;
using gt = greater<int>;
using minq = priority_queue<int, vector<int>, gt>;
using P = pair<ll, ll>;
template <class T> void takeUnique(vector<T> &v) {
  auto last = std::unique(v.begin(), v.end());
  v.erase(last, v.end());
}
const ll LINF = 1e18L + 1;
const int INF = 1e9 + 1;
int dx[] = {0, 1, 0, -1};
int dy[] = {1, 0, -1, 0};
int dxx[] = {0, 1, 1, 1, 0, -1, -1, -1};
int dyy[] = {1, 1, 0, -1, -1, -1, 0, 1};
// clang++ -std=c++11 -stdlib=libc++

string s;
int main() {
  cin >> s;
  bool hard = true;
  rep(i, s.size()) {
    if (i & 1) {
      if (s[i] <= 'Z' and s[i] >= 'A')
        hard &= true;
      else
        hard &= false;
    } else {
      if (s[i] <= 'z' and s[i] >= 'a')
        hard &= true;
      else
        hard &= false;
    }
  }
  if (hard)
    puts("Yes");
  else
    puts("No");
  return 0;
}
