Language: C++

using System;
using System.Linq;

class Program
{
    static void Main(string[] args) {
        int[] s = Console.ReadLine().Split().Select(int.Parse).ToArray();
        int n = s[0];
        int m = s[1];
        int[][] l = new int[m][];
        for (int i = 0; i < m; i ++) {
            l[i] = new int[4];
            int[] a = Console.ReadLine().Split().Select(int.Parse).ToArray();
            l[i][0] = i;
            l[i][1] = a[0];
            l[i][2] = a[1];
        }
        Array.Sort(l, (a, b) => a[2] - b[2]);
        int[] c = new int[n];
        for(int i = 0; i < m; i ++) {
            c[l[i][1]-1] ++;
            l[i][3] = c[l[i][1]-1];
        }
        Array.Sort(l, (a, b) => a[0] - b[0]);
        for(int i = 0; i < m; i ++) {
            Console.WriteLine(String.Format("{0:D6}", l[i][1]) + String.Format("{0:D6}", l[i][3]));
        }
    }
}

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:6:22: error: 'string' has not been declared
    6 |     static void Main(string[] args) {
      |                      ^~~~~~
a.cc:6:31: error: expected ',' or '...' before 'args'
    6 |     static void Main(string[] args) {
      |                               ^~~~
a.cc:29:2: error: expected ';' after class definition
   29 | }
      |  ^
      |  ;
a.cc: In static member function 'static void Program::Main(int*)':
a.cc:7:12: error: structured binding declaration cannot have type 'int'
    7 |         int[] s = Console.ReadLine().Split().Select(int.Parse).ToArray();
      |            ^~
a.cc:7:12: note: type must be cv-qualified 'auto' or reference to cv-qualified 'auto'
a.cc:7:12: error: empty structured binding declaration
a.cc:7:15: error: expected initializer before 's'
    7 |         int[] s = Console.ReadLine().Split().Select(int.Parse).ToArray();
      |               ^
a.cc:8:17: error: 's' was not declared in this scope
    8 |         int n = s[0];
      |                 ^
a.cc:10:12: error: structured binding declaration cannot have type 'int'
   10 |         int[][] l = new int[m][];
      |            ^~
a.cc:10:12: note: type must be cv-qualified 'auto' or reference to cv-qualified 'auto'
a.cc:10:12: error: empty structured binding declaration
a.cc:10:14: error: expected initializer before '[' token
   10 |         int[][] l = new int[m][];
      |              ^
a.cc:12:13: error: 'l' was not declared in this scope
   12 |             l[i] = new int[4];
      |             ^
a.cc:13:16: error: structured binding declaration cannot have type 'int'
   13 |             int[] a = Console.ReadLine().Split().Select(int.Parse).ToArray();
      |                ^~
a.cc:13:16: note: type must be cv-qualified 'auto' or reference to cv-qualified 'auto'
a.cc:13:16: error: empty structured binding declaration
a.cc:13:19: error: expected initializer before 'a'
   13 |             int[] a = Console.ReadLine().Split().Select(int.Parse).ToArray();
      |                   ^
a.cc:15:23: error: 'a' was not declared in this scope
   15 |             l[i][1] = a[0];
      |                       ^
a.cc:18:9: error: 'Array' was not declared in this scope
   18 |         Array.Sort(l, (a, b) => a[2] - b[2]);
      |         ^~~~~
a.cc:18:20: error: 'l' was not declared in this scope
   18 |         Array.Sort(l, (a, b) => a[2] - b[2]);
      |                    ^
a.cc:18:24: error: 'a' was not declared in this scope
   18 |         Array.Sort(l, (a, b) => a[2] - b[2]);
      |                        ^
a.cc:18:27: error: 'b' was not declared in this scope
   18 |         Array.Sort(l, (a, b) => a[2] - b[2]);
      |                           ^
a.cc:18:31: error: expected primary-expression before '>' token
   18 |         Array.Sort(l, (a, b) => a[2] - b[2]);
      |                               ^
a.cc:19:12: error: structured binding declaration cannot have type 'int'
   19 |         int[] c = new int[n];
      |            ^~
a.cc:19:12: note: type must be cv-qualified 'auto' or reference to cv-qualified 'auto'
a.cc:19:12: error: empty structured binding declaration
a.cc:19:15: error: expected initializer before 'c'
   19 |         int[] c = new int[n];
      |               ^
a.cc:21:13: error: 'c' was not declared in this scope
   21 |             c[l[i][1]-1] ++;
      |             ^
a.cc:24:31: error: expected primary-expression before '>' token
   24 |         Array.Sort(l, (a, b) => a[0] - b[0]);
      |                               ^
a.cc:26:13: error: 'Console' was not declared in this scope
   26 |             Console.WriteLine(String.Format("{0:D6}", l[i][1]) + String.Format("{0:D6}", l[i][3]));
      |             ^~~~~~~
a.cc:26:31: error: 'String' was not declared in this scope
   26 |             Console.WriteLine(String.Format("{0:D6}", l[i][1]) + String.Format("{0:D6}", l[i][3]));
      |                               ^~~~~~