/* >>>>>Shwetal<<<<< */
#include <bits/stdc++.h>
#define int long long
#define f(i, begin, end) for (__typeof(end) i = (begin) - ((begin) > (end)); i != (end) - ((begin) > (end)); i += 1 - 2 * ((begin) > (end)))
#define inputArray(arr) f(i, 0, arr.size()) cin >> arr[i]
#define printArray(arr) f(i, 0, arr.size()) cout << arr[i] << ' '; cout << endl
#define endl '\n'
typedef long long ll;
const int mod = 1e9+7;
using namespace std;

bool solve() {
    string s;
    cin >> s;
    int n = s.size();
    // bool flag = true;
    f(i, 0, n){
        if(i % 2 == 1 && islower(s[i])){
            return false;
        }
        if(i % 2 == 0 && isupper(s[i])){
            return false;
        }
    }
    return true;
    
}

int32_t main(){
    // freopen("input.txt","r",stdin); freopen("output.txt","w",stdout);
    ios::sync_with_stdio(0);
    cin.tie(0);
    int T = 1;
    // cin >> T;
    while(T--){
        // solve();
        if(solve())
            cout << "Yes" << endl;
        else
            cout << "No" << endl;
    }
    return 0;
}
#include <bits/stdc++.h>
using namespace std;

int main() {
  string S;
  cin >> S;

  for (int i = 0; i < (int)S.size(); i++) {
    if ((i % 2 == 0) && (S.at(i) < 'a' || S.at(i) > 'z')) {
      cout << "No" << endl;
      return 0;
    }

    else if ((i % 2 == 1) && (S.at(i) < 'A' || S.at(i) > 'Z')) {
      cout << "No" << endl;
      return 0;
    }
  }

  cout << "Yes" << endl;
}