using System;
using System.Linq;
using System.Diagnostics;
using System.Text.RegularExpressions;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            string str = "+123-456/7890";
            var onlyNumbers = Convert.ToInt64(Regex.Replace(str, "[^0-9]+", ""));
        
        }
    }
}