// input: 'a' -> output: "YES"
// input: '?' -> output: "NO"
// input: 'B' -> output: "YES"
// input: '*' -> output: "NO"

bool isAlpha(char in) {
  //put your code here.
}

#include <iostream>
int main() {
  char input;
  std::cin >> input;
  //put your code here
}