01: #include <iostream>
02: #include <string>
03: #include <cmath>
04: 
05: using namespace std;
06: 
07: int main()
08: {  
09:    double area;
10:    cout << "Please enter the area of a square: ";
11:    cin >> area;
12: 
13:    if (cin.fail())
14:    {
15:       cout << "Error: Bad input\n";
16:       return 1;
17:    }
18: 
19:    if (area < 0)
20:    {
21:       cout << "Error: Negative area.\n";
22:       return 1;
23:    }
24: 
25:    cout << "The side length is " << sqrt(area) << "\n";
26: 
27:    return 0;
28: }