#include <bits/stdc++.h>
#define pb push_back
#define all(a) a.begin(),a.end()
#define forn(i,n) for(int i=0;i<int(n);i++)
#define forr(i,n) for(int i=int(n-1);i>=0;i--)
#define fora(i,a,b) for(int i=int(a);i<=int(b);i++)
#define forb(i,a,b) for(int i=int(a);i>=int(b);i--)
#define kickstart int t,o;cin>>o;for(t=1;t<=o;t++){cout<<"Case #"<<t<<": ";solve();}
#define mod 1000000007
using namespace std;
using ll=long long int;
typedef vector<int> vi;
typedef pair<int,int> pi;
typedef vector<ll> vii;
typedef pair<ll ,ll> pii;

void solve()
{
    string s;
    cin >> s;
    bool hard = 1;
    for (int i = 0; i < s.size(); i++) {
        if (i % 2 == 0) {
            if (islower(s[i]) == false) {
                hard = 0;
            }
        } 
        else {
            if (isupper(s[i]) == false) {
                hard = 0;
            }
        }
    }
    if (hard == false) cout << "No";
    else cout << "Yes";
}

int main()
{
    ios::sync_with_stdio(0); 
    cin.tie(0); 
    cout.tie(0);
    int t=1;
    //cin>>t;
    while(t--)
	solve();
    return 0;
}
#include<bits/stdc++.h>
using namespace std;

int main() {
  string s;
  cin >> s;
  bool ans = true;
  for (int i=0; i < s.length(); i++) {
    if (i % 2 == 0) {
      if (islower(s.at(i))) continue;
      else ans = false; break;
    } 
    else {
      if (isupper(s.at(i))) continue;
      else ans = false; break;
    }
  }
  if (ans) cout << "Yes" << endl;
  else cout << "No" << endl;
}