using System;
using System.Collections.Generic;
using System.Linq;

internal class Program
{
    private const bool handfree_ = true; //определяет вручную ли вводятся данные или рандомом

    public static void Main()
    {
        try
        {
            var a = InitArray().ToArray();
            PrintArray(a);

            var positive = IsPositiveFirst(a);
            var k = 0;
            for (var i = 0; i < a.Length; i++)
            {
                if (positive && a[k] < a[i] || !positive && a[k] > a[i])
                    k = i;
            }

            a[k] = a[k] * a[k];
            PrintArray(a);
        }

        catch(Exception e)
        {
            Console.ForegroundColor = ConsoleColor.Red;
            Console.WriteLine(e);
        }
        finally
        {
            Console.ReadLine();
        }
    }

    public static IEnumerable<int> InitArray()
    {
        var random = new Random(DateTime.Now.Millisecond);
        int n;
        if (handfree_)
            n = random.Next(100);
        else
        {
            Console.Write("n = ");
            n = int.Parse(Console.ReadLine());
        }

        var result = new int[n];

        for (var i = 0; i < result.Length; i++)
        {
            result[i] = handfree_ ? random.Next(-100, 100) : int.Parse(Console.ReadLine());
        }

        return result;
    }

    public static void PrintArray(IEnumerable<int> a)
    {
        Console.Write("Array:");
        foreach (var element in a)
        {
            Console.Write($" {element}");
        }

        Console.WriteLine();
    }

    public static bool IsPositiveFirst(IEnumerable<int> a)
    {
        foreach (var element in a)
        {
            if (element == 0)
                continue;

            return element > 0;
        }

        throw new Exception("Array is empty");
    }
}