#include <iostream>   
#include <string>

using namespace std;

int main()
{

  char letter;

  cout << "Please enter your letter grade: ";
  cin >> letter;

  switch(letter){

  case 'A':
  case 'a': cout << "Your performance is exceptional.\n";
    break;
  case 'B':
  case 'b': cout << "Your performance is pretty swell.\n";
    break;
  case 'C':
  case 'c': cout << "Your performance is average, but that's ... OK.\n";
    break;
  case 'D':
  case 'd': cout << "You're not doing so well.\n";
    break;
  default: cout << "See you again next semester.\n";
    break;
  }

  return 0;
}