#include <bits/stdc++.h>

using namespace std;

int main()
{
  
  int i;
  bool flag=false;
  string s;
  cin >> s;
  
  for(i=0;i<s.length();i++)
  {
  	if (i%2==0 && !(s[i]>='a' && s[i]<='z'))
  	{
  		flag=true;
  		break;
  	}
  	if (i%2!=0 && !(s[i]>='A' && s[i]<='Z'))
  	{
  		flag=true;
  		break;
  	}
  }
  
  if(flag) cout << "No" << endl;
  else cout << "Yes" << endl;
  
  return 0;
}
                              //ABHISHEK AGRAWAL,BIT mesra//                    
                      //Newbie......You have to be odd to be no. ONE :)//
//Authhor: Abhishekagrawal 
//Date: 20/02/2021 
//Time: 17:30:13 
#include<bits/stdc++.h>
using namespace std;
#define ll long long int
#define ld long double
#define fl float
#define vll vector<ll>
#define pii pair<int,int>
#define vpll vector<pair<ll,ll>>
#define pb push_back
#define f first
#define s second
#define mll map<ll,ll>
#define mp make_pair
#define sp(n) fixed<<setprecision(n)
#define mod (ll)1000000007
#define sortv(v) sort(v.begin(),v.end())
#define INF (ll)(1e15)
#define loop(i,n) for(int i=0;i<n;i++)
#define loop1(i,n) for(int i=1;i<=n;i++)
#define rloop(n,i) for(int i=n-1;i>=0;i--)
#define sorta(a) sort(a,a+n,greater<ll>())
#define countone(n) __builtin_popcount(n)
#define numoftrailzero(n) __builtin_ctz(n)
#define maxpowoftwo(n) __builtin_clz(n)
#define leastindexwithone(n)  __builtin_ffs(n)
#define what_is(x) cerr << #x << " is " << x << endl;
#define pfv(v) cout<<v.size()<<"\n";loop(i,v.size()) cout<<v[i]<<" ";cout<<"\n";
#define pv(v) loop(i,v.size()) cout<<v[i]<<" ";
#define all(v) v.begin(),v.end()
#define mset(dp,val) memset(dp,val,sizeof(dp))
 ll test,n;ll sum,ans;
// #ifdef TESTING 
// #define DEBUG fprintf(stderr, "====TESTING====\n") 
// #define VALUE(x) cerr << "The value of " << #x << " is " << x << endl 
// #define debug(...) fprintf(stderr, __VA_ARGS__) 
// #else 
// #define DEBUG 
// #define VALUE(x) 
// #define debug(...) 
// #endif
void the_happiest_place_on_earth()
{
    ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL); 
  #ifdef ENABLE_FILE_IO
    freopen("out.txt", "r", stdin);
    freopen("out1.txt", "w", stdout);
  #endif      
} 
// bool comp(const pair<ll,ll> &a, const pair<ll,ll> &b){
//   if(a.s+2*a.f==b.s+2*b.f) return a.f>b.f;
//   return (a.s+2*a.f>b.s+2*b.f);
// }
const int N=200040;ll a[N],b[N],c[N],par[N],Size[N],present[N],color[N];
void testcase(){
  string s;
  cin>>s;
  n=s.length();
  loop(i,n){
    if(i&1){
      if(s[i]>='a'){cout<<"No";return;}
    }
    else{
      if(s[i]<='Z'){cout<<"No";return;}
    }
  }
  cout<<"Yes";
  return;
}

int main(){
  the_happiest_place_on_earth();
  // Today's thought: Push yourself,because no one else is going to do it for you.
  // Things are not always #000000 and #FFFFFF
  // START OF PROGRAM LOGIC
  // g++ -o a BB.cpp -DENABLE_FILE_IO;./a
  // g++ -std=c++17 -Wshadow -Wall -g -fsanitize=address -fsanitize=undefined -D_GLIBCXX_DEBUG -o a file_name.cpp;./a
  test=1;int t=0;
  // cin>>test;  
  while(test--){
    //cout<<"Case #"<<++t<<": ";
    testcase();
  } 
  cerr << "Time : " << 1000 *((double)clock()) / (double)CLOCKS_PER_SEC << "ms\n";
  // //END OF PROGRAM LOGIC
  return 0;
}
/* stuff you should look for
    * int overflow, array bounds
    * special cases (n=1?)
    * do smth instead of nothing and stay organized
    * WRITE STUFF DOWN
    * DON'T GET STUCK ON ONE APPROACH
*/