#include <iostream>
#include <cmath>

using namespace std;

void inputScores (double& s1, double& s2, double& s3, double& s4);
// Precondition: The user is ready to enter four numbers. 
// Postcondition: The values of s1, s2, s3, and s4 are set to the 
// four numbers entered by the user.


void computeStats (double s1, double s2, double s3, double s4,
                   double& avg, double& stdev);
// Precondition: The parameters s1, s2, s3, and s4 contain four numbers.
// Postcondition: The parameters avg and stdev have been set to
// the average and standard deviation, respectively, of the four numbers.


double average (double s1, double s2, double s3, double s4);
// Precondition: The parameters s1, s2, s3, and s4 contain four numbers.
// Returns the average of s1, s2, s3, and s4.


double standardDeviation (double s1, double s2, double s3, double s4, double avg);
// Precondition: The parameters s1, s2, s3, and s4 contain four real numbers 
// and the parameter avg contains the average of the four numbers.
// Returns the standard deviation of s1, s2, s3, and s4.

void printStats (double s1, double s2, double s3, double s4, 
		 double avg, double stdev);
// Precondition: The parameters avg and stdev contain the average
// and standard deviation of the four numbers s1, s2, s3, s4.
// Postcondition: The four numbers along with their average and
// standard deviation have been printed to the screen.



int main ()
{

  double score1, score2, score3, score4;
  double avg, stdev;
  char ans;    // answer to "four more numbers?" question


  do {


    inputScores (score1, score2, score3, score4);
    computeStats (score1, score2, score3, score4, avg, stdev);
    printStats (score1, score2, score3, score4, avg, stdev);


    cout << endl;
    cout << "Try four more numbers (y or n)? ";
    cin >> ans;
    cout << endl;
  }
  while (ans == 'y' || ans == 'Y');

  return 0;
}


void inputScores (double& s1, double& s2, double& s3, double& s4)
{
  cout << "Enter four scores, separated by blank spaces: ";
  cin >> s1 >> s2 >> s3 >> s4;
  cout << endl;
}


	// --------------------------------
	// ----- ENTER YOUR CODE HERE -----
	// --------------------------------


	// --------------------------------
	// --------- END USER CODE --------
	// --------------------------------


void printStats (double s1, double s2, double s3, double s4, 
		 double avg, double stdev)
{
  cout << "The average of " << s1 << ", " << s2 << ", " << s3
       << ", and " << s4 << " is " << avg 
       << " and the standard deviation is " << stdev << endl;

}

void computeStats (double s1, double s2, double s3, double s4, double& avg, double& stdev)
{
   avg = average(s1,s2,s3,s4);
   stdev = standardDeviation(s1,s2,s3,s4,avg);
}