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

#define pb push_back
#define mp make_pair
#define lb lower_bound
#define ub upper_bound
#define ff first
#define ss second

#define rep(i, n) for(int i = 0; i < n; ++i)
#define repR(i, n) for (int i = n-1; i >= 0; --i)
#define repA(i, a, n) for (int i = a; i <= n; ++i)
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define sz(x) (int)(x).size()
#define mem1(a) memset(a,-1,sizeof(a))
#define mem0(a) memset(a,0,sizeof(a))

typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<double, double> pdd;

#define vi vector<int>
#define vvi vector<vi>
#define vll vector<ll>
#define vvll vector<vll>
#define vs vector<string>
#define vd vector<double>
#define vb vector<bool>

#define vpii vector<pii>
#define vpll vector<pll>
#define vpdd vector<pdd>

#define mod 1000000007
#define ps(x,y) fixed << setprecision(y) << x
#define fastio ios_base::sync_with_stdio(false),cin.tie(NULL),cout.tie(NULL)

void solve()
{
	string s;
	cin >> s;

	rep(i, s.length()) {
		if (i % 2 == 0) {
			if (s[i] < 97 || s[i] > 122) {
				cout << "No" << '\n';
				return;
			}
		}
		else {
			if (s[i] < 65 || s[i] > 90) {
				cout << "No" << '\n';
				return;
			}
		}
	}

	cout << "Yes" << '\n';
}

int main()
{
	fastio;

#ifndef ONLINE_JUDGE
	freopen("input.txt", "r", stdin);
	freopen("output.txt", "w", stdout);
#endif

	int t = 1;
	//cin>>t;
	while (t--) solve();

	return 0;
}
#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
#include <set>
#include <unordered_map>
#include <stack>
#include <math.h>
#include <queue>
#include <functional>
#include <iomanip>
using namespace std;

#define ll long long

bool comp(pair<int,int> a, pair<int,int> b){
    return a.first<b.first;
}

const int N=1000001;

bool solve(string s){
    for(int i=0; i<s.length();i++){
        char c= s.at(i);
        if(i%2==0){
            if(c-tolower(c)!=0) return true;
        } else{
            if(c-toupper(c)!=0) return true;
        }
    }
    return false;
}

int main(){

    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    string s;
    cin>>s;
    cout<<(solve(s) ? "No":"Yes")<<"\n";

    
    return 0;
}