Problema de novato

[Tikitios]

Lo tengo resuelto, iria asi:
__________________
#include <stdlib.h>
#include <iostream>
#include <stdio.h>

using namespace std;
int main()
{
char z;
int grade;
int aCount = 0, bCount = 0, cCount = 0, dCount = 0, fCount = 0;

cout << "Ingresa la letra de tu nota\nPresiona ctrl+z para finalizar.\n";

while ( (grade = getchar() ) != EOF) {
switch (grade) {
case 'A': case 'a':
++aCount;
break;
case 'B' : case 'b':
++bCount;
break;
case 'C' : case 'c':
++cCount;
break;
case 'D' : case 'd':
++dCount;
break;
case 'F' : case 'f':
++fCount;
break;
case '\n' : case ' ':
break;

default:
cout << "Letra incorrecta.\nIngresa nueva letra.\n";
break;
}
}
cout <<"\nEl total de notas es:\n";
cout <<"A: "<< aCount <<".\n";
cout <<"B: "<< bCount <<".\n";
cout <<"C: "<< cCount <<".\n";
cout <<"D: "<< dCount <<".\n";
cout <<"F: "<< fCount <<".\n";

system("PAUSE");
return 0;
}
____________
Me sirvio lo que dijo _Licifer_ eso del ctrl+z, gracias.