/*
    author : Aryan Agarwal, IIT KGP
    created : 20-February-2021 17:32:16 IST
*/

#include <bits/stdc++.h>
using namespace std;
#define int long long

const int mxn = 1e5;
const long long INF = 2e18;
const int32_t M = 1000000007; /*more than 1e9 */ /*7 + 1e9*/
// const int32_t M = 998244353; /*less than 1e9 */   /*1 + 7*17*(1<<23) */
const long double pie = acos(-1);

#define X first
#define Y second
#define pb push_back
#define sz(a) ((int)(a).size())
#define all(a) (a).begin(), (a).end()
#define F(i, a, b) for (int i = a; i <= b; i++)
#define RF(i, a, b) for (int i = a; i >= b; i--)

#define dbg(...) __f(#__VA_ARGS__, __VA_ARGS__)
template <typename Arg1>
void __f(const char* name, Arg1&& arg1){
  cerr << name << " : " << arg1 << std::endl;
}
template <typename Arg1, typename... Args>
void __f(const char* names, Arg1&& arg1, Args&&... args){
  const char* comma = strchr(names + 1, ',');cerr.write(names, comma - names) << " : " << arg1<<" | ";__f(comma+1, args...);
}

void solve_LOG()
{
    string s;
    cin>>s;
    s='#'+s;

    F(i,1,sz(s)-1)
    {
        if(i%2)
        {
            if(s[i]<'a' || s[i]>'z')
            {
                cout<<"No";
                return;
            }
        }
        if(i%2==0)
        {
            if(s[i]<'A' || s[i]>'Z')
            {
                cout<<"No";
                return;
            }
        }
    }

    cout<<"Yes";
}

signed main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
#ifndef ONLINE_JUDGE
// freopen("input.txt","r",stdin);
// freopen("output.txt","w",stdout);
#endif
#ifdef ARYAN_SIEVE
    // defualt mxn_sieve = 1e5
    sieve();
#endif
#ifdef ARYAN_SEG_SIEVE
    // default [L,R] = [1,1e5]
    segmented_sieve();
#endif
#ifdef ARYAN_FACT
    // default mxn_fact = 1e5
    fact_init();
#endif
    // cout<<fixed<<setprecision(10);
    int _t=1;
    // cin>>_t;
    for (int i=1;i<=_t;i++)
    {
        // cout<<"Case #"<<i<<": ";
        solve_LOG();
    }
    return 0;
}
#include<bits/stdc++.h>
using namespace std;
int main()
{
	bool b=true;
	char a[10000];
	cin>>a;
	for(int i=0;i<strlen(a);i++)
	{
		if(i%2==0)
		{
			if(a[i]<97||a[i]>122)
			{
				b=false;
				break;
			}
		}
		else
		{
			if(a[i]<65||a[i]>90)
			{
				b=false;
				break;
			}
		}
	}
	if(b==true)
	{
		cout<<"Yes";
	}
	else
	{
		cout<<"No";
	}
	return 0;
}