```
import <iostream>;
import <numbers>;
import <iomanip>; // for setprecision() function
import <format>; // for format() function
#include <cmath>
using namespace std;
int main() {
const double fish_factor { 2.0 / 0.5};
const double cm_per_meter { 100 };
double fish_count = {};
double fish_length = {};
cout << "\nEnter the number of fish you want to keep: ";
cin >> fish_count;
cout << "Enter the average fish length in centimeters: ";
cin >> fish_length;
fish_length /= cm_per_meter; // Convert to meters
cout << endl;
const double pond_area {fish_count * fish_length * fish_factor};
const double pond_diameter {2.0* sqrt(pond_area / M_PI)};
cout << "Pond diameter required for " << fish_count << " fish is " << pond_diameter
<< " meters.\n";
cout << "Pond diameter required for " << fish_count << " fish is " << setprecision(3) << pond_diameter
<< " meters.\n";
cout << format("Pond diameter required for {} fish is {} meters.\n\n", fish_count, pond_diameter);
return 0;
}
```