using System;
using System.Text.RegularExpressions;
class Program
{
static String move_special_characters_to_beginning(String s) {
int len = s.Length;
var regx = new Regex("[a-zA-Z0-9]");
String chars = "", pecial_characters = "";
for (int i = 0; i < len; i++) {
char ch = s[i];
if (regx.IsMatch(ch.ToString()))
chars = chars + ch;
else
pecial_characters = pecial_characters + ch;
}
return pecial_characters + chars;
}
static void Main() {
String s = "c++$vb.net&%java*() php c# <>/python 3.7.3";
Console.WriteLine(move_special_characters_to_beginning(s));
}
}
/*
run:
++$.&%*() # <>/ ..cvbnetjavaphpcpython373
*/
