#include <algorithm>
#include <iterator>
#include <iostream>

template<class T, class U>
class Summer {
public:
    Summer() : m_n(0) , m_sum(0) {}
    void operator() (const T& n) {
        std::cout << "operator() running: " << n << std::endl;
        m_n++;
        m_sum += n;
    }
    int count() const {
        return m_n;
    }
    T sum() const {
        return m_sum;
    }
    U mean() const {
        return (m_n != 0) ? m_sum / m_n : 0;
    }
private:
    int m_n;
    T m_sum;
};

using namespace std;

int main() {
    cout << "Input data end with ctrl+D" << endl;
    Summer<int,float> sum;
    for_each(istream_iterator<int>(cin),istream_iterator<int>(),sum);
//    Summer<int, double> sum = for_each(istream_iterator<int>(cin), istream_iterator<int>(),
//                        Summer<int, double>());

        cout << "count: " << sum.count() << endl << "sum: " << sum.sum() << endl
             << "mean: " << sum.mean() << endl; 
}