// p02_02.cpp: The average of some positive numbers.
#include <iostream>
using namespace std;

int main() {

double x, sum =0;
int n = 0;
cout << "Enter some positive numbers, followed by a\n"
        "negative number:\n";
for (;;) {
cin >> x;
if (x < 0) break;
sum += x;
++n;
}

if (n == 0)
 cout << "No numbers read.\n";
else
 cout << "Average: " << sum/n << endl;

return 0;

}