using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Text.RegularExpressions; using System.Threading.Tasks; class MainClass { public static string QuestionsMarks(string str) { string clean = Regex.Replace(str, @"([^\d\?])", string.Empty); var matches = Regex.Matches(clean, @"(\d)(\?{3})(\d)"); var results = new List<int>(); foreach (Match m in matches){ int a = Convert.ToInt32(m.Value.First().ToString()); int b = Convert.ToInt32(m.Value.Last().ToString()); results.Add(a+b); } string final = results.Count != 0 && results.All<int>(r => r == 10) ? "true" : "false"; return final; } // keep this function call here static void Main() { Console.WriteLine(QuestionsMarks(Console.ReadLine())); } }