// Format specifiers for std::format()

import <iostream>;

import <format>;

import <numbers>; // For the pi constant

#include <cmath> // For the square root function

int main()

{

// 2 square feet pond surface for every 6 inches of fish

const double fish_factor{ 2.0 / 0.5 }; // Area per unit length of fish

const unsigned int inches_per_foot{ 12 };

unsigned int fish_count{}; // Number of fish

double fish_length{}; // Average length of fish

std::cout << "Enter the number of fish you want to keep: ";

std::cin >> fish_count;

std::cout << "Enter the average fish length in inches: ";

std::cin >> fish_length;

fish_length /= inches_per_foot; // Convert to feet

std::cout << '\n';

// Calculate the required surface area

const double pond_area{ fish_count * fish_length * fish_factor };

// Calculate the pond diameter from the area

const double pond_diameter{ 2.0 * std::sqrt(pond_area / std::numbers::pi) };

std::cout << std::format("Pond diameter required for {} fish is {:.2} feet.\n",

fish_count, pond_diameter);

}