Multidimensional Arrays - 3. Primary Diagonal

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

namespace Advanced
{
    class Program
    {
        static void Main(string[] args)
        {
            int dimentions = int.Parse(Console.ReadLine());

            int rows = dimentions;
            int cols = dimentions;

            var matrix = new int[rows, cols];

            for (int row = 0; row < rows; row++)
            {
                var currentRow = Console.ReadLine()
                .Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries)
                .Select(int.Parse)
                .ToArray();

                for (int col = 0; col < cols; col++)
                {
                    matrix[row, col] = currentRow[col];
                }
            }

            int primaryRow = 0;
            int primaryCol = 0;
            var sum = 0;

            while (true)
            {
                if (primaryRow < 0
                    || primaryRow >= matrix.GetLength(0)
                    || primaryCol < 0
                    || primaryCol >= matrix.GetLength(1))
                {
                    break;
                }

                sum += matrix[primaryRow, primaryCol];
                primaryRow++;
                primaryCol++;
            }
            Console.WriteLine(sum);
        }
    }
}