#include <iostream>
#include <fstream>
#include <sstream>
#include <string>
using namespace std;

// illustrates use of input string streams

int main()
{
    ifstream ifile;
    ifile.open("data.txt");
    if (ifile.fail())
    {
        cout << "file not opened" << endl;  
        return 0;
    }
    string s;
    string name, lastname;
    int total, count, num;
    cout << "program computes averages of lines of numbers of a file named data.txt"  << endl;
    cout << "Each line should start with name and lastname followed by several grades" << endl << endl;

    while (getline(ifile,s))
    {   
        total = 0;
        count = 0;

        istringstream input(s);
        input >> name >> lastname;

        while (input >> num)
        {   count++;
            total += num;
        }
        if (count != 0)
        {   cout << name << " " << lastname << ": average of " << count << " grades = "
                 << double(total)/count << endl;     
        }
        else
        {   cout << name << " " << lastname << ": wrong or no input!" << endl;
        }
    }
    return 0;
}