#include <stdio.h>
#include <math.h>

double square(double x);

main()
{
  double x, xsquared;
  printf("x?");
  if ( scanf("%lf", &x) != 1)
    {
      printf("error");
      exit(1);
    }

  printf("x = %lf\n", x);

  xsquared = square(x);
  printf("x^2 = %lf\n", xsquared);
  exit(0);
}
double square(double x)
{ 
  return x*x;
}