11-5.cpp

#include <numeric>
#include <iostream>
#include <vector>

using namespace std;

int main( ) {
  vector<int> v;
  v.push_back(1);
  v.push_back(2);
  v.push_back(3);
  v.push_back(4);
  int sum = accumulate(v.begin( ), v.end( ), 0);
  double mean = double(sum) / v.size( );
  cout << "sum = " << sum << endl;
  cout << "count = " << v.size( ) << endl;
  cout << "mean = " << mean << endl;
}