Language: C++

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using static System.Console;

namespace For_Atcoder
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(ReadLine());
            string[] a = ReadLine().Split(' ');
            string[] b = ReadLine().Split(' ');

            int[] output = new int[(Convert.ToString((int.Parse(a.Max()) + int.Parse(b.Max())),2)).Length];
            for (int i = 0;i < a.Length; i++)
            {
                for(int j = 0; j < b.Length; j++)
                {
                    string bin = Convert.ToString((int.Parse(a[i]) + int.Parse(b[j])), 2);
                    
                    for(int k = bin.Length - 1; k >= 0; k--)
                    {
                        output[bin.Length - 1 - k] += int.Parse(bin.Substring(k, 1));
                    }
                }
            }
            int ans = output.Select((x, w) => (x % 2) * (int)Math.Pow(2,w)).Sum();

            WriteLine(ans);
        }
    }
}

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.Generic;
      |       ^~~~~~
a.cc:3:7: error: expected nested-name-specifier before 'System'
    3 | using System.Linq;
      |       ^~~~~~
a.cc:4:7: error: expected nested-name-specifier before 'System'
    4 | using System.Text;
      |       ^~~~~~
a.cc:5:7: error: expected nested-name-specifier before 'static'
    5 | using static System.Console;
      |       ^~~~~~
a.cc:11:26: error: 'string' has not been declared
   11 |         static void Main(string[] args)
      |                          ^~~~~~
a.cc:11:35: error: expected ',' or '...' before 'args'
   11 |         static void Main(string[] args)
      |                                   ^~~~
a.cc:34:6: error: expected ';' after class definition
   34 |     }
      |      ^
      |      ;
a.cc: In static member function 'static void For_Atcoder::Program::Main(int*)':
a.cc:13:21: error: expected primary-expression before 'int'
   13 |             int n = int.Parse(ReadLine());
      |                     ^~~
a.cc:14:13: error: 'string' was not declared in this scope
   14 |             string[] a = ReadLine().Split(' ');
      |             ^~~~~~
a.cc:14:20: error: expected primary-expression before ']' token
   14 |             string[] a = ReadLine().Split(' ');
      |                    ^
a.cc:15:20: error: expected primary-expression before ']' token
   15 |             string[] b = ReadLine().Split(' ');
      |                    ^
a.cc:17:16: error: structured binding declaration cannot have type 'int'
   17 |             int[] output = new int[(Convert.ToString((int.Parse(a.Max()) + int.Parse(b.Max())),2)).Length];
      |                ^~
a.cc:17:16: note: type must be cv-qualified 'auto' or reference to cv-qualified 'auto'
a.cc:17:16: error: empty structured binding declaration
a.cc:17:19: error: expected initializer before 'output'
   17 |             int[] output = new int[(Convert.ToString((int.Parse(a.Max()) + int.Parse(b.Max())),2)).Length];
      |                   ^~~~~~
a.cc:18:32: error: 'a' was not declared in this scope
   18 |             for (int i = 0;i < a.Length; i++)
      |                                ^
a.cc:20:36: error: 'b' was not declared in this scope
   20 |                 for(int j = 0; j < b.Length; j++)
      |                                    ^
a.cc:22:28: error: expected ';' before 'bin'
   22 |                     string bin = Convert.ToString((int.Parse(a[i]) + int.Parse(b[j])), 2);
      |                            ^~~
a.cc:24:33: error: 'bin' was not declared in this scope
   24 |                     for(int k = bin.Length - 1; k >= 0; k--)
      |                                 ^~~
a.cc:26:25: error: 'output' was not declared in this scope
   26 |                         output[bin.Length - 1 - k] += int.Parse(bin.Substring(k, 1));
      |                         ^~~~~~
a.cc:26:55: error: expected primary-expression before 'int'
   26 |                         output[bin.Length - 1 - k] += int.Parse(bin.Substring(k, 1));
      |                                                       ^~~
a.cc:30:23: error: 'output' was not declared in this scope
   30 |             int ans = output.Select((x, w) => (x % 2) * (int)Math.Pow(2,w)).Sum();
      |                       ^~~~~~
a.cc:30:38: error: 'x' was not declared in this scope
   30 |             int ans = output.Select((x, w) => (x % 2) * (int)Math.Pow(2,w)).Sum();
      |                                      ^
a.cc:30:41: error: 'w' was not declared in this scope
   30 |             int ans = output.Select((x, w) => (x % 2) * (int)Math.Pow(2,w)).Sum();
      |                                         ^
a.cc:30:45: error: expected primary-expression before '>' token
   30 |             int ans = output.Select((x, w) => (x % 2) * (int)Math.Pow(2,w)).Sum();
      |                                             ^
a.cc:30:62: error: 'Math' was not declared in this scope
   30 |             int ans = output.Select((x, w) => (x % 2) * (int)Math.Pow(2,w)).Sum();
      |                                                              ^~~~
a.cc:32:13: error: 'WriteLine' was not declared in this scope
   32 |             WriteLine(ans);
      |             ^~~~~~~~~