#include <iostream>
#include <string>
#include <iomanip>
using namespace std;

int main()				
{
	int N; 			
	string L;
	double S1, S2, S, W, D;
	while (true)		   
	{
	  S1 = 0.0;
	  S2 = 0.0;
	  cout<<"# of items? ";	 
	  cin>>N;
	  int I=1;	
	  while (I <= N)
	  {
		cout<<"Letter? ";
		cin>>L;
		if (L == "A")
			W = 4.0;
		else
		if (L == "B")
			W = 3.0;
		else
		if (L == "C")
			W = 2.0;		     
		else
		if (L == "D")
			W = 1.0;		     
		else
			W = 0.0;		       
		cout<<"Credits? ";
		cin>>D;
		S2 = S2 + D;
		S1 = S1 + D * W;		
		I = I + 1;
	  }
	  S = S1 / S2;
	  cout<<"GPA="<<setprecision(3)<<S<<"\n";
	  cout<<"Any more to process? ";
	  string ans;
	  cin>>ans;
	  if (ans == "N")
		  break;
	}// end of outer while
	system("PAUSE");
	return 0;
}