using System;

using System.Globalization;

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var Dateformats = new[] { "M/d/yyyy", "M/dd/yyyy", "MM/d/yyyy", "MM/dd/yyyy", "yyyy-MM-dd" };

DateTime parsedDateThas;

DateTime.TryParseExact("12/30/1987", Dateformats, CultureInfo.InvariantCulture, DateTimeStyles.None, out parsedDateThas);

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Console.WriteLine(parsedDateThas.ToString("dd-MM-yyyy"));