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

#define REP(i, n) for(ll i=0;i<ll(n);i++)
#define FOR(i, a, b) for(ll i=a;i<=ll(b);i++)

int read_int() {
    int n;
    scanf("%d", &n);
    return n;
}

int main() {
    string S;
    bool flag = true;
    cin >> S;
    REP(i, S.length()) {
        if (i%2 == 1){
            if (islower(S[i])) flag = false;
        }
        else {
            if (isupper(S[i])) flag = false;
        }
    }
    if (flag) cout << "Yes" << endl;
    else cout << "No" << endl;

    return 0;
}
#include <iostream>
#include <cstdio>
#include <algorithm>
using namespace std;

string s;

int main()
{
	cin >> s;
	for (int i = 0; i < s.size(); i++)
		if (!((i % 2 == 0 && s[i] >= 'a' && s[i] <= 'z') || (i % 2 == 1 && s[i] >= 'A' && s[i] <= 'Z')))
		{
			cout << "No";
			return 0;
		}
	cout << "Yes";
	return 0;
}