Language: C++

using System;
using System.Linq;

class P
{
    static void Main()
    {
        Console.WriteLine(Enumerable.Repeat(0, int.Parse(Console.ReadLine())).Select(_ => Console.ReadLine().Split().Select(long.Parse).ToArray()).OrderByDescending(x => x[0] + x[1]).Select((x, y) => new Tuple<long[], int>(x, y)).Aggregate(0L, (x, y) => y.Item2 % 2 == 0 ? x + y.Item1[0] : x - y.Item1[1]));
    }
}


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.Linq;
      |       ^~~~~~
a.cc:10:2: error: expected ';' after class definition
   10 | }
      |  ^
      |  ;
a.cc: In static member function 'static void P::Main()':
a.cc:8:9: error: 'Console' was not declared in this scope
    8 |         Console.WriteLine(Enumerable.Repeat(0, int.Parse(Console.ReadLine())).Select(_ => Console.ReadLine().Split().Select(long.Parse).ToArray()).OrderByDescending(x => x[0] + x[1]).Select((x, y) => new Tuple<long[], int>(x, y)).Aggregate(0L, (x, y) => y.Item2 % 2 == 0 ? x + y.Item1[0] : x - y.Item1[1]));
      |         ^~~~~~~
a.cc:8:27: error: 'Enumerable' was not declared in this scope
    8 |         Console.WriteLine(Enumerable.Repeat(0, int.Parse(Console.ReadLine())).Select(_ => Console.ReadLine().Split().Select(long.Parse).ToArray()).OrderByDescending(x => x[0] + x[1]).Select((x, y) => new Tuple<long[], int>(x, y)).Aggregate(0L, (x, y) => y.Item2 % 2 == 0 ? x + y.Item1[0] : x - y.Item1[1]));
      |                           ^~~~~~~~~~
a.cc:8:48: error: expected primary-expression before 'int'
    8 |         Console.WriteLine(Enumerable.Repeat(0, int.Parse(Console.ReadLine())).Select(_ => Console.ReadLine().Split().Select(long.Parse).ToArray()).OrderByDescending(x => x[0] + x[1]).Select((x, y) => new Tuple<long[], int>(x, y)).Aggregate(0L, (x, y) => y.Item2 % 2 == 0 ? x + y.Item1[0] : x - y.Item1[1]));
      |                                                ^~~
a.cc:8:86: error: '_' was not declared in this scope
    8 |         Console.WriteLine(Enumerable.Repeat(0, int.Parse(Console.ReadLine())).Select(_ => Console.ReadLine().Split().Select(long.Parse).ToArray()).OrderByDescending(x => x[0] + x[1]).Select((x, y) => new Tuple<long[], int>(x, y)).Aggregate(0L, (x, y) => y.Item2 % 2 == 0 ? x + y.Item1[0] : x - y.Item1[1]));
      |                                                                                      ^
a.cc:8:89: error: expected primary-expression before '>' token
    8 |         Console.WriteLine(Enumerable.Repeat(0, int.Parse(Console.ReadLine())).Select(_ => Console.ReadLine().Split().Select(long.Parse).ToArray()).OrderByDescending(x => x[0] + x[1]).Select((x, y) => new Tuple<long[], int>(x, y)).Aggregate(0L, (x, y) => y.Item2 % 2 == 0 ? x + y.Item1[0] : x - y.Item1[1]));
      |                                                                                         ^
a.cc:8:125: error: expected primary-expression before 'long'
    8 |         Console.WriteLine(Enumerable.Repeat(0, int.Parse(Console.ReadLine())).Select(_ => Console.ReadLine().Split().Select(long.Parse).ToArray()).OrderByDescending(x => x[0] + x[1]).Select((x, y) => new Tuple<long[], int>(x, y)).Aggregate(0L, (x, y) => y.Item2 % 2 == 0 ? x + y.Item1[0] : x - y.Item1[1]));
      |                                                                                                                             ^~~~
a.cc:8:166: error: 'x' was not declared in this scope
    8 |         Console.WriteLine(Enumerable.Repeat(0, int.Parse(Console.ReadLine())).Select(_ => Console.ReadLine().Split().Select(long.Parse).ToArray()).OrderByDescending(x => x[0] + x[1]).Select((x, y) => new Tuple<long[], int>(x, y)).Aggregate(0L, (x, y) => y.Item2 % 2 == 0 ? x + y.Item1[0] : x - y.Item1[1]));
      |                                                                                                                                                                      ^
a.cc:8:169: error: expected primary-expression before '>' token
    8 |         Console.WriteLine(Enumerable.Repeat(0, int.Parse(Console.ReadLine())).Select(_ => Console.ReadLine().Split().Select(long.Parse).ToArray()).OrderByDescending(x => x[0] + x[1]).Select((x, y) => new Tuple<long[], int>(x, y)).Aggregate(0L, (x, y) => y.Item2 % 2 == 0 ? x + y.Item1[0] : x - y.Item1[1]));
      |                                                                                                                                                                         ^
a.cc:8:195: error: 'y' was not declared in this scope
    8 |         Console.WriteLine(Enumerable.Repeat(0, int.Parse(Console.ReadLine())).Select(_ => Console.ReadLine().Split().Select(long.Parse).ToArray()).OrderByDescending(x => x[0] + x[1]).Select((x, y) => new Tuple<long[], int>(x, y)).Aggregate(0L, (x, y) => y.Item2 % 2 == 0 ? x + y.Item1[0] : x - y.Item1[1]));
      |                                                                                                                                                                                                   ^
a.cc:8:199: error: expected primary-expression before '>' token
    8 |         Console.WriteLine(Enumerable.Repeat(0, int.Parse(Console.ReadLine())).Select(_ => Console.ReadLine().Split().Select(long.Parse).ToArray()).OrderByDescending(x => x[0] + x[1]).Select((x, y) => new Tuple<long[], int>(x, y)).Aggregate(0L, (x, y) => y.Item2 % 2 == 0 ? x + y.Item1[0] : x - y.Item1[1]));
      |                                                                                                                                                                                                       ^
a.cc:8:205: error: 'Tuple' does not name a type
    8 |         Console.WriteLine(Enumerable.Repeat(0, int.Parse(Console.ReadLine())).Select(_ => Console.ReadLine().Split().Select(long.Parse).ToArray()).OrderByDescending(x => x[0] + x[1]).Select((x, y) => new Tuple<long[], int>(x, y)).Aggregate(0L, (x, y) => y.Item2 % 2 == 0 ? x + y.Item1[0] : x - y.Item1[1]));
      |                                                                                                                                                                                                             ^~~~~
a.cc:8:211: error: expected primary-expression before 'long'
    8 |         Console.WriteLine(Enumerable.Repeat(0, int.Parse(Console.ReadLine())).Select(_ => Console.ReadLine().Split().Select(long.Parse).ToArray()).OrderByDescending(x => x[0] + x[1]).Select((x, y) => new Tuple<long[], int>(x, y)).Aggregate(0L, (x, y) => y.Item2 % 2 == 0 ? x + y.Item1[0] : x - y.Item1[1]));
      |                                                                                                                                                                                                                   ^~~~
a.cc:8:219: error: expected primary-expression before 'int'
    8 |         Console.WriteLine(Enumerable.Repeat(0, int.Parse(Console.ReadLine())).Select(_ => Console.ReadLine().Split().Select(long.Parse).ToArray()).OrderByDescending(x => x[0] + x[1]).Select((x, y) => new Tuple<long[], int>(x, y)).Aggregate(0L, (x, y) => y.Item2 % 2 == 0 ? x + y.Item1[0] : x - y.Item1[1]));
      |                                                                                                                                                                                                                           ^~~
a.cc:8:253: error: expected primary-expression before '>' token
    8 |         Console.WriteLine(Enumerable.Repeat(0, int.Parse(Console.ReadLine())).Select(_ => Console.ReadLine().Split().Select(long.Parse).ToArray()).OrderByDescending(x => x[0] + x[1]).Select((x, y) => new Tuple<long[], int>(x, y)).Aggregate(0L, (x, y) => y.Item2 % 2 == 0 ? x + y.Item1[0] : x - y.Item1[1]));
      |                                                                                                                                                                                                                                                             ^