uses
  System;

var
  arr: array [,] of integer;

begin
  Console.Write('Введите размер квадратной матрицы: ');
  var n := Convert.ToInt32(Console.ReadLine());

  SetLength(arr, n, n);

  Console.WriteLine('Исходня матрица: ');
  for var i := 0 to arr.GetLength(0) - 1 do
  begin
    for var j := 0 to arr.GetLength(1) - 1 do
    begin
      arr[i, j] := PABCSystem.Random(51) - 25;
      Console.Write('{0,4}', arr[i, j]);
    end;
    Console.WriteLine();
  end;

  Console.Write('Введите номер строки для замены (1 <= K <= ' + n + '): ');
  var k := Convert.ToInt32(Console.ReadLine());

  for var i := 0 to arr.GetLength(0) - 1 do
  begin
    var temp := arr[i, k - 1];
    arr[i, k - 1] := arr[k - 1, i];
    arr[k - 1, i] := temp;
  end;

  Console.WriteLine('Новая матрица: ');
  for var i := 0 to arr.GetLength(0) - 1 do
  begin
    for var j := 0 to arr.GetLength(1) - 1 do
      Console.Write('{0,4}', arr[i, j]);
    Console.WriteLine();
  end;
end.