#include <iostream> 
using namespace std; 
  
char getGrade() 
{ 
  // step 1
  char result = 'X'; // the default value 

  // step 2
  while (true) 
  { 
    cout << "What is your grade? [A, B, C, D, F, or X to quit]: "; 
    cin >> result; 
    cin.ignore(1000, 10); 

    if (result == 'A' || result == 'B' || result == 'C') break; 
    if (result == 'D' || result == 'F') break; 
    if (result == 'X' || result == 'x') break; 

    cout << result << " is not a valid grade. Try again..." << endl; 
  } // while 

  // step 3
  return result; 
} // getGrade 
  
int main() 
{ 
  char grade; 
  while (true) 
  { 
    grade = getGrade(); 
    if (grade == 'X' || grade == 'x') break; 
    if (grade == 'A' || grade == 'B' || grade == 'C') 
      cout << "You pass" << endl; 
  } // while 
  
  cout << "Thanks for checking your grades!" << endl; 
} // main