#include <iostream>
using namespace std;

#include <cmath>

int main()
{
  int a = 81;
  double b = 81;

  cout << "This works on SOME compilers, but not all:" << endl;
  cout << "The square root of " << a << " is " << sqrt(a) << endl;

  cout << "But this works on ALL compilers:" << endl;
  cout << "The square root of " << a << " is " << sqrt((double)a) << endl;

  cout << "And this ALWAYS works, because sqrt expects a double:" << endl;
  cout << "The square root of " << b << " is " << sqrt(b) << endl;
}