this[system.int32] is not resolved in int.Parse(input[1]); #596

struct Trip : IComparable<Trip>
{
	public int cost;
	public int days;
	public int CompareTo(Trip other)
	{
		return -this.cost.CompareTo(other.cost);
	}
}

public static void Main()
{
	int n = int.Parse(Console.ReadLine());
	var trips = new Trip[n];
	for (int i = 0; i < n; i++)
	{
		var input = Console.ReadLine().Split(' ');
		trips[i].cost = int.Parse(input[1]);
		trips[i].days = int.Parse(input[0]);
	}
	Array.Sort(trips);//sort by cost descending
	int[,] totalProfit = new int[n + 1, n + 1];
	int maxProfit = 0;
	for (int i = 0; i < n; i++)
	{
		for (int j = 0; j < n; j++)
		{
			totalProfit[i + 1, j + 1] =
			Math.Max(totalProfit[i, j] + trips[i].cost * (trips[i].days - j),
					totalProfit[i + 1, j + 1]);
			totalProfit[i + 1, j] =
			Math.Max(totalProfit[i + 1, j],
					totalProfit[i, j]);
			maxProfit = Math.Max(maxProfit, totalProfit[i + 1, j + 1]);
		}
	}
	Console.WriteLine(maxProfit);
}