using System;
public class Program {
public static void Main() {
String s = "abc 9836 xy%^(s 21 * 9 ppp 100";
String digits = "";
foreach (char ch in s) {
if (!Char.IsDigit(ch)) {
continue;
}
digits += ch;
}
Console.WriteLine(digits);
}
}
/*
run:
9836219100
*/