/**

▂▃▅▇█▓▒░۩۞۩ ۩۞۩░▒▓█▇▅▃▂
 In the name of Allah

       _           _
      / /         \ \
     / / _   _   _ \ \
    < < (_) (_) (_) > >
     \ \           / /
      \_\         /_/

  Nerede Gitsen Çukur Orda

**/

#include<bits/stdc++.h>
#include<fstream>
///#include<conio.h>
///#include "windows.h"
#define ll long long
#define ld long double
#define pb push_back
#define pf push_front
#define fr first
#define sc second
#define Qodirov_Kamoliddin ios_base::sync_with_stdio(0) ; cin.tie(NULL) ; cout.tie(NULL) ;
#define p_b pop_back
#define p_f pop_front
#define quluq return 0;
#define NO cout << "NO" << endl ;
#define no cout << "no" << endl ;
#define YES cout << "YES" << endl ;
#define yes cout << "yes" << endl ;

using namespace std ;

    const ll N = 1e19 + 0 ;

string g ;

void vkoshp()
{
    cin >> g ;
    for (ll i = 0 ; i < g.size() ; i += 2)
    {
        if (g[i] >= 'A' and g[i] <= 'Z')
        {
            cout << "No" << endl ;
            return ;
        }
    }
    for (ll i = 1 ; i < g.size() ; i += 2)
    {
        if (g[i] >= 'a' and g[i] <= 'z')
        {
            cout << "No" << endl ;
            return ;
        }
    }
    cout << "Yes" << endl ;
}

int main ()
{
    //freopen("input.txt", "r", stdin );
    //freopen("output.txt", "w", stdout );
    Qodirov_Kamoliddin
    ///Author of the Greatest code : Murtazoev Alijon
    ///4294967295
    ll Qu_l_uQ = 1 ;
    // cin >> Qu_l_uQ ;
    while ( Qu_l_uQ -- )
        vkoshp() ;
}
///MaaN studios
///Eco students

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef long double ld;

#define fi first
#define se second
#define pb push_back
#define mp make_pair



int main(){
	ios_base::sync_with_stdio(0); cin.tie(0);
	string s; cin>>s;
	int n = s.length();
	string ans = "Yes";
	for(int i=0; i<n; i++){
		if(i%2==0 && s[i]>=(char)'A' && s[i]<=(char)'Z'){
			ans = "No";
			break;
		}
		if(i%2==1 && s[i]>=(char)'a' && s[i]<=(char)'z'){
			ans = "No";
			break;
		}
	}
	cout<<ans;
	
}
