Language: C++

using System;
using System.Collections;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.Linq;
using System.Numerics;

namespace AtCoderWorkspace
{
    public class Solver
    {
        public void Solve()
        {
            var cin = new Scanner();
            var a = cin.nextInt();
            var b = cin.nextInt();
            var c = cin.nextInt();

            var arr = new int[] { a, b, c};
            Array.Sort(arr);
            Array.Reverse(arr);
            
            Console.WriteLine(int.Parse("" + arr[0] + arr[1]) + arr[2]);
        }
    }

    class Scanner
    {
        string[] s;
        int i;

        char[] cs = new char[] { ' ' };

        public Scanner()
        {
            s = new string[0];
            i = 0;
        }

        public string next()
        {
            if (i < s.Length) return s[i++];
            string st = Console.ReadLine();
            while (st == "") st = Console.ReadLine();
            s = st.Split(cs, StringSplitOptions.RemoveEmptyEntries);
            if (s.Length == 0) return next();
            i = 0;
            return s[i++];
        }

        public int nextInt()
        {
            return int.Parse(next());
        }
        public int[] ArrayInt(int N, int add = 0)
        {
            int[] Array = new int[N];
            for (int i = 0; i < N; i++)
            {
                Array[i] = nextInt() + add;
            }
            return Array;
        }

        public int[] DPArrayInt(int N, int ex)
        {
            int[] Array = new int[N + ex];
            for (int i = 0; i < N; i++)
            {
                Array[i] = nextInt();
            }
            return Array;
        }

        public long nextLong()
        {
            return long.Parse(next());
        }

        public long[] ArrayLong(int N, long add = 0)
        {
            long[] Array = new long[N];
            for (int i = 0; i < N; i++)
            {
                Array[i] = nextLong() + add;
            }
            return Array;
        }

        public long[] DPArrayLong(int N, int ex)
        {
            long[] Array = new long[N + ex];
            for (int i = 0; i < N; i++)
            {
                Array[i] = nextLong();
            }
            return Array;
        }

        public double nextDouble()
        {
            return double.Parse(next());
        }


        public double[] ArrayDouble(int N, double add = 0)
        {
            double[] Array = new double[N];
            for (int i = 0; i < N; i++)
            {
                Array[i] = nextDouble() + add;
            }
            return Array;
        }
    }

    class Program
    {
        static void Main(string[] s) => new Solver().Solve();
    }
}


Compiler output:
a.cc:1:7: error: expected nested-name-specifier before 'System'
    1 | using System;
      |       ^~~~~~
a.cc:2:7: error: expected nested-name-specifier before 'System'
    2 | using System.Collections;
      |       ^~~~~~
a.cc:3:7: error: expected nested-name-specifier before 'System'
    3 | using System.Collections.Generic;
      |       ^~~~~~
a.cc:4:7: error: expected nested-name-specifier before 'System'
    4 | using System.Collections.Specialized;
      |       ^~~~~~
a.cc:5:7: error: expected nested-name-specifier before 'System'
    5 | using System.Linq;
      |       ^~~~~~
a.cc:6:7: error: expected nested-name-specifier before 'System'
    6 | using System.Numerics;
      |       ^~~~~~
a.cc:10:5: error: expected unqualified-id before 'public'
   10 |     public class Solver
      |     ^~~~~~
a.cc:29:9: error: 'string' does not name a type
   29 |         string[] s;
      |         ^~~~~~
a.cc:32:13: error: expected unqualified-id before '[' token
   32 |         char[] cs = new char[] { ' ' };
      |             ^
a.cc:34:15: error: expected ':' before 'Scanner'
   34 |         public Scanner()
      |               ^~~~~~~~
      |               :
a.cc:40:15: error: expected ':' before 'string'
   40 |         public string next()
      |               ^~~~~~~
      |               :
a.cc:40:16: error: 'string' does not name a type
   40 |         public string next()
      |                ^~~~~~
a.cc:51:15: error: expected ':' before 'int'
   51 |         public int nextInt()
      |               ^~~~
      |               :
a.cc:55:15: error: expected ':' before 'int'
   55 |         public int[] ArrayInt(int N, int add = 0)
      |               ^~~~
      |               :
a.cc:55:19: error: expected unqualified-id before '[' token
   55 |         public int[] ArrayInt(int N, int add = 0)
      |                   ^
a.cc:65:15: error: expected ':' before 'int'
   65 |         public int[] DPArrayInt(int N, int ex)
      |               ^~~~
      |               :
a.cc:65:19: error: expected unqualified-id before '[' token
   65 |         public int[] DPArrayInt(int N, int ex)
      |                   ^
a.cc:75:15: error: expected ':' before 'long'
   75 |         public long nextLong()
      |               ^~~~~
      |               :
a.cc:80:15: error: expected ':' before 'long'
   80 |         public long[] ArrayLong(int N, long add = 0)
      |               ^~~~~
      |               :
a.cc:80:20: error: expected unqualified-id before '[' token
   80 |         public long[] ArrayLong(int N, long add = 0)
      |                    ^
a.cc:90:15: error: expected ':' before 'long'
   90 |         public long[] DPArrayLong(int N, int ex)
      |               ^~~~~
      |               :
a.cc:90:20: error: expected unqualified-id before '[' token
   90 |         public long[] DPArrayLong(int N, int ex)
      |                    ^
a.cc:100:15: error: expected ':' before 'double'
  100 |         public double nextDouble()
      |               ^~~~~~~
      |               :
a.cc:106:15: error: expected ':' before 'double'
  106 |         public double[] ArrayDouble(int N, double add = 0)
      |               ^~~~~~~
      |               :
a.cc:106:22: error: expected unqualified-id before '[' token
  106 |         public double[] ArrayDouble(int N, double add = 0)
      |                      ^
a.cc:115:6: error: expected ';' after class definition
  115 |     }
      |      ^
      |      ;
a.cc: In constructor 'AtCoderWorkspace::Scanner::Scanner()':
a.cc:36:13: error: 's' was not declared in this scope
   36 |             s = new string[0];
      |             ^
a.cc:36:21: error: 'string' does not name a type
   36 |             s = new string[0];
      |                     ^~~~~~
a.cc: In member function 'int AtCoderWorkspace::Scanner::nextInt()':
a.cc:53:20: error: expected primary-expression before 'int'
   53 |             return int.Parse(next());
      |                    ^~~
a.cc:53:20: error: expected ';' before 'int'
a.cc:53:23: error: expected unqualified-id before '.' token
   53 |             return int.Parse(next());
      |                       ^
a.cc: In member function 'long int AtCoderWorkspace::Scanner::nextLong()':
a.cc:77:20: error: expected primary-expression before 'long'
   77 |             return long.Parse(next());
      |                    ^~~~
a.cc:77:20: error: expected ';' before 'long'
a.cc:77:24: error: expected unqualified-id before '.' token
   77 |             return long.Parse(next());
      |                        ^
a.cc: In member function 'double AtCoderWorkspace::Scanner::nextDouble()':
a.cc:102:20: error: expected primary-expression before 'double'
  102 |             return double.Parse(next());
      |                    ^~~~~~
a.cc:102:20: error: expected ';' before 'double'
a.cc:102:26: error: expected unqualified-id before '.' token
  102 |             return double.Parse(next());
      |                          ^
a.cc: At global scope:
a.cc:119:26: error: 'string' has not been declared
  119 |         static void Main(string[] s) => new Solver().Solve();
      |                          ^~~~~~
a.cc:119:35: error: expected ',' or '...' before 's'
  119 |         static void Main(string[] s) => new Solver().Solve();
      |                                   ^
a.cc:119:41: error: invalid pure specifier (only '= 0' is allowed) before 'new'
  119 |         static void Main(string[] s) => new Solver().Solve();
      |                                         ^~~
a.cc:119:21: error: initializer specified for static member function 'static void AtCoderWorkspace::Program::Main(int*)'
  119 |         static void Main(string[] s) => new Solver().Solve();
      |                     ^~~~
a.cc:120:6: error: expected ';' after class definition
  120 |     }
      |      ^
      |      ;