#include<bits/stdc++.h>
using namespace std;
const int N = 1e6 + 5, M = 1e3 + 5;
#define int long long
#define double long double
#define fio ios_base::sync_with_stdio(false);cin.tie(NULL);
char s[1111];
void solve() {
    cin>>s+1;
    for(int i=1;i<=strlen(s+1);i++){
        if(i&1) {
            if(s[i]>='A'&&s[i]<='Z') {
                cout<<"No"<<endl;
                return;
            }
        }
        else{
            if(s[i]>='a'&&s[i]<='z') {
                cout<<"No"<<endl;
                return;
            }
        }
    }
    cout<<"Yes"<<endl;
}
signed main() {
    fio;
    solve();

    return 0;
}
#include<bits/stdc++.h>
#define inf 1e18
#define endl "\n"
#define loop(i,x,y) for(int i = x; i < y ; i++ )
#define in(n)       int n; cin>>n;
#define inarr(arr,n) int arr[n]; for(int i = 0; i < n ; i++){cin>>arr[i];}
#define maploop(x) for(auto itr = x.begin(); itr != x.end();itr++)
#define int long long
using namespace std;
const int N = 10001;
int mod = 1000000007;


void Main()
{
	string s;
	cin >> s;
	loop(i, 0, s.size())
	{
		if (i % 2 == 1)
		{
			if (s[i] >= 'A' && s[i] <= 'Z')
			{
				continue;
			}
			else
			{
				cout << "No" << endl;
				return;
			}
		}
		else
		{
			if (s[i] >= 'a' && s[i] <= 'z')
			{
				continue;
			}
			else
			{
				cout << "No" << endl;
				return;
			}
		}

	}
	cout << "Yes" << endl;



}


int32_t main()
{
	srand(time(0));
	ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
	int t = 1;
	//cin >> t;
	while (t--)
	{
		Main();
	}
}