5.3.15

using System;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace myloyorrr
{
    internal class Program
    {
        static void In(int[,] a)
        {
            for (int i = 0; i < a.GetLength(0); i++)
            {
                string[]s = Console.ReadLine().Split();

                for (int j = 0; j < a.GetLength(1); j++)
                {
                    a[i, j] = int.Parse(s[j]);

                }

            }
        }
        static void Out(int[,] a)
        {
            for (int i = 0; i < a.GetLength(0); i++)
            {
                for (int j = 0; j < a.GetLength(1); j++)
                {
                    Console.Write(a[i, j] + " ");
                }
                Console.WriteLine();
            }
        }

        static int det(int[,] a)
        {
            int ans = 0;
            int k = 1;
            if(a.GetLength(0) == 1)
            {
                ans =  a[0, 0];
            }
            else if(a.GetLength(0) == 2)
            {
                ans = a[0, 0] * a[1, 1] - a[0, 1] * a[1, 0];
            }
            else if(a.GetLength(0) >= 3)
            {
                for(int j = 0; j < a.GetLength(1); j++)
                {
                    int[,] b;
                    b = new int[a.GetLength(0)-1, a.GetLength(0)-1];

                    for (int x = 1; x < a.GetLength(0); x++)
                    {
                        for (int y = 0; y < a.GetLength(1); y++)
                        {
                            if(y < j)
                            {
                                b[x - 1, y] = a[x, y];
                            }
                            else if(y > j)
                            {
                                b[x - 1, y-1] = a[x, y];
                            }
                        }
                    }
                    ans += k * a[0, j] * det(b);
                    k *= (-1);
                }
            }
            return ans;
        }

        static void Main()
        {
            int[,] a;
            int n = int.Parse(Console.ReadLine());
            a = new int[n, n];
            In(a);
            Console.WriteLine(det(a));
            //Out(a);
        }
    }
}