using System;

using System.Text;

using System.Text.RegularExpressions;

​

public class Program

{

    public static void Main()

    {

        string input = "10:131186;";

        MatchCollection mCol = Regex.Matches(input, "\\d+");

        StringBuilder sb = new StringBuilder();

        foreach (Match m in mCol)

        {

            sb.Append(m.Value);

        }

        Console.WriteLine(sb);

    }

}