Program for square root calculating

// Square Root
// Coded by informaticar

#include <cstdlib>
#include <iostream>
#include <cmath>

using namespace std;

int main()
{
    float a, b;
    cin >> a;
    if (a < 0)
    {
          cout << "Number is negative." << endl;
          }
          else
          {
              b = sqrt(a);
              cout << b << endl;
              }
              system("pause");
              return 0;
              }