#include <iostream.h>
#include <math.h>
int main ()
{
   int n;
   double a, sum, sum2, mean, mean_error, sigma;
   n=0;
   sum=0;
   sum2=0;
   while (cin >> a ) {
     n = n + 1;
     sum = sum + a;
     sum2 = sum2 + a*a;
  } 
  mean = sum/n;
  sigma = sqrt(sum2/n - mean*mean);
  mean_error = sigma/(n-1);
  cout <<"no. of data ="<< n <<", mean ="<<mean<<"+-"<<
  mean_error << ", sigma ="<<sigma<<endl;
  return(0);
}