#include<iostream>
#include<cstring>
#include<cstdio>
#include<algorithm>
#include<string>

using namespace std;

signed main(){
    ios::sync_with_stdio(false);
    string str;
    cin>>str;
    bool flag=true;
    for(int i=0;i<str.size();++i){
        if(i&1){
            if(str[i]<'A'||str[i]>'Z'){
                flag=false;
                break;
            }
        }
        else{
            if(str[i]<'a'||str[i]>'z'){
                flag=false;
                break;
            }
        }
    }
    if(flag) cout<<"Yes\n";
    else cout<<"No\n";
    return 0;
}
#include<iostream>
using namespace std;
typedef long long li;
#define yn(i) print((i)?"Yes":"No")
#define rep(i,n) for(int i=0;i<(n);i++)
#define df 0
template<class T> void print(const T& t){ cout << t << "\n"; }
template<class T, class... Ts> void print(const T& t, const Ts&... ts) { cout << t; if (sizeof...(ts)) cout << " "; print(ts...); }

int diff(string s){
  int n=s.size();
  rep(i,n){
    if((s[i]<'a')!=(i%2==1)) return 0;
  }
  return 1;
}

int main(){
  string s; cin >>s;
  yn(diff(s));
}
