do-while loop

#include"stdafx.h"
#include"iostream"
usingnamespace std;
void main()
{
float total_grade=0.0;
float grade_avg = 0.0;
float grade;
int grade_ctr = 0;
do
{
cout <<"What is your grade? (-1 to end) "<<endl;
cin >> grade;
if (grade >= 0.0)
{
total_grade += grade;
grade_ctr ++;
}
}
while (grade >= 0.0);
grade_avg = (total_grade / grade_ctr);
{
cout <<"\nYou made a total of "<<total_grade<<" points.\n";
cout <<"Your average was "<< grade_avg <<"\n";
}
if (total_grade >= 450.0)
{
cout <<"** You made an A!!";
}
system("pause");
}