#include<bits/stdc++.h>
#define int long long
#define ll long long
#define speed ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL)
#define fs first
#define sd second
#define rept(x,n) for(int i=x;i<n;i++)
#define rrept(n,x) for(int i=n-1;i>=x;i--)
#define all(v) v.begin(),v.end()
#define mpit map<int,int>::iterator
#define stit set<int,int>::iterator
#define quit queue<int,int>::iterator
#define maxt(a,b,c) max(a,max(b,c))
#define mint(a,b,c) min(a,min(b,c))
#define rsort(v) sort(v.rbegin(),v.rend())
#define pb push_back
#define prnt(a,n) for(int i=0;i<n;i++)cout<<a[i]<<" ";
using namespace std;
void solve()
{
     string s;
     cin>>s;
     for(ll i = 0;i<s.length();i+=2)
     {
         if(s[i]>='a'&&s[i]<='z')
            continue;
         else
         {
             cout<<"No\n";
             return;
         }
     }
     for(ll i = 1;i<s.length();i+=2)
     {
         if(s[i]>='A'&&s[i]<='Z')
            continue;
         else
         {
             cout<<"No\n";
             return;
         }
     }
     cout<<"Yes\n";
}
signed main()
{
    speed;
    int t=1;
    //cin>>t;
    while(t--)
    {
         solve();
    }
    return 0;
}

#include <bits/stdc++.h>
#define fr first
#define se second
#define ll long long
#define pb push_back
using namespace std;
 
const ll INF = 1e16 + 1;
const ll N = 2e3 + 5;
const ll mod = 1e9 + 7;
const long double eps = 1E-7;

ll n, m, cnt;
int main()
{
	string s;
	cin >> s;
	for ( int i=0; i<s.size(); i+=2 ){
		if ( s[i] >= 'A' and s[i] <= 'Z' ){
			cout << "No";
			return 0;
		}
	}
	for ( int i=1; i<s.size(); i+=2 ){
		if ( s[i] >= 'a' and s[i] <= 'z' ){
			cout << "No";
			return 0;
		}
	}
	cout << "Yes";
}