#include<bits/stdc++.h>
using namespace std;
int main()
{
    char s[105];
    int a=0;
    cin.getline(s,105);
    if(s[0]<='z' and s[0]>='a'){
            cout<<"No";
            return 0;
        }
    for(int i=1;s[i]!='\0';i+=1){
        if(s[i]<='Z' and s[i]>='A'){
            cout<<"No";
            return 0;
        }
        
	}
	cout<<"Yes";
	return 0;
}