Language: C++

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;

using Pair = System.Collections.Generic.KeyValuePair<int, int>;

class Program
{
	public Program() { }

	static void Main(string[] args)
	{
		new Program().prog();
	}
	Scanner cin;
	const int MOD = 1000000007;
	const int INF = int.MaxValue;
	const double EPS = 1e-7;
	const double PI = 3.1415926536;

	void prog()
	{
		cin = new Scanner();
		int[,] dir8 = new int[8, 2] { { -1, -1 }, { -1, 0 }, { -1, 1 }, { 0, -1 }, { 0, 1 }, { 1, -1 }, { 1, 0 }, { 1, 1 } };
		int[,] dir4 = new int[4, 2] { { -1, 0 }, { 0, -1 }, { 0, 1 }, { 1, 0 } };

		long A = cin.nextInt();
		long B = cin.nextInt();
		long C = cin.nextInt();
		if (A % 2 == 0 || B % 2 == 0 || C % 2 == 0)
		{
			Console.WriteLine(0);
			return;
		}
		long max = Math.Max(A, Math.Max(B, C));
		if (max == A)
		{
			Console.WriteLine(B * C);
			return;
		}else if (max == B)
		{
			Console.WriteLine(A * C);
			return;
		}
		else
		{
			Console.WriteLine(A * B);
			return;
		}
	}
}

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);
		i = 0;
		return next();
	}

	public int nextInt()
	{
		return int.Parse(next());
	}

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

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

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 'System'
    5 | using System.IO;
      |       ^~~~~~
a.cc:7:14: error: 'System' does not name a type
    7 | using Pair = System.Collections.Generic.KeyValuePair<int, int>;
      |              ^~~~~~
a.cc:11:15: error: expected ':' before 'Program'
   11 |         public Program() { }
      |               ^~~~~~~~
      |               :
a.cc:13:26: error: 'string' has not been declared
   13 |         static void Main(string[] args)
      |                          ^~~~~~
a.cc:13:35: error: expected ',' or '...' before 'args'
   13 |         static void Main(string[] args)
      |                                   ^~~~
a.cc:17:9: error: 'Scanner' does not name a type
   17 |         Scanner cin;
      |         ^~~~~~~
a.cc:53:2: error: expected ';' after class definition
   53 | }
      |  ^
      |  ;
a.cc:19:25: error: expected primary-expression before 'int'
   19 |         const int INF = int.MaxValue;
      |                         ^~~
a.cc: In static member function 'static void Program::Main(int*)':
a.cc:15:30: error: expected ';' before '.' token
   15 |                 new Program().prog();
      |                              ^
a.cc: In member function 'void Program::prog()':
a.cc:25:17: error: 'cin' was not declared in this scope
   25 |                 cin = new Scanner();
      |                 ^~~
a.cc:25:27: error: expected type-specifier before 'Scanner'
   25 |                 cin = new Scanner();
      |                           ^~~~~~~
a.cc:26:21: error: expected identifier before ',' token
   26 |                 int[,] dir8 = new int[8, 2] { { -1, -1 }, { -1, 0 }, { -1, 1 }, { 0, -1 }, { 0, 1 }, { 1, -1 }, { 1, 0 }, { 1, 1 } };
      |                     ^
a.cc:26:21: error: expected ']' before ',' token
a.cc:26:20: error: structured binding declaration cannot have type 'int'
   26 |                 int[,] dir8 = new int[8, 2] { { -1, -1 }, { -1, 0 }, { -1, 1 }, { 0, -1 }, { 0, 1 }, { 1, -1 }, { 1, 0 }, { 1, 1 } };
      |                    ^
a.cc:26:20: note: type must be cv-qualified 'auto' or reference to cv-qualified 'auto'
a.cc:26:20: error: empty structured binding declaration
a.cc:26:24: error: expected initializer before 'dir8'
   26 |                 int[,] dir8 = new int[8, 2] { { -1, -1 }, { -1, 0 }, { -1, 1 }, { 0, -1 }, { 0, 1 }, { 1, -1 }, { 1, 0 }, { 1, 1 } };
      |                        ^~~~
a.cc:27:21: error: expected identifier before ',' token
   27 |                 int[,] dir4 = new int[4, 2] { { -1, 0 }, { 0, -1 }, { 0, 1 }, { 1, 0 } };
      |                     ^
a.cc:27:21: error: expected ']' before ',' token
a.cc:27:20: error: structured binding declaration cannot have type 'int'
   27 |                 int[,] dir4 = new int[4, 2] { { -1, 0 }, { 0, -1 }, { 0, 1 }, { 1, 0 } };
      |                    ^
a.cc:27:20: note: type must be cv-qualified 'auto' or reference to cv-qualified 'auto'
a.cc:27:20: error: empty structured binding declaration
a.cc:27:24: error: expected initializer before 'dir4'
   27 |                 int[,] dir4 = new int[4, 2] { { -1, 0 }, { 0, -1 }, { 0, 1 }, { 1, 0 } };
      |                        ^~~~
a.cc:34:25: error: 'Console' was not declared in this scope
   34 |                         Console.WriteLine(0);
      |                         ^~~~~~~
a.cc:37:28: error: 'Math' was not declared in this scope
   37 |                 long max = Math.Max(A, Math.Max(B, C));
      |                            ^~~~
a.cc:40:25: error: 'Console' was not declared in this scope
   40 |                         Console.WriteLine(B * C);
      |                         ^~~~~~~
a.cc:44:25: error: 'Console' was not declared in this scope
   44 |                         Console.WriteLine(A * C);
      |                         ^~~~~~~
a.cc:49:25: error: 'Console' was not declared in this scope
   49 |                         Console.WriteLine(A * B);
      |                         ^~~~~~~
a.cc: At global scope:
a.cc:57:9: error: 'string' does not name a type
   57 |         string[] s;
      |         ^~~~~~
a.cc:60:13: error: expected unqualified-id before '[' token
   60 |         char[] cs = new char[] { ' ' };
      |             ^
a.cc:62:15: error: expected ':' before 'Scanner'
   62 |         public Scanner()
      |               ^~~~~~~~
      |               :
a.cc:68:15: error: expected ':' before 'string'
   68 |         public string next()
      |               ^~~~~~~
      |               :
a.cc:68:16: error: 'string' does not name a type
   68 |         public string next()
      |                ^~~~~~
a.cc:78:15: error: expected ':' before 'int'
   78 |         public int nextInt()
      |               ^~~~
      |               :
a.cc:83:15: error: expected ':' before 'long'
   83 |         public long nextLong()
      |               ^~~~~
      |               :
a.cc:88:15: error: expected ':' before 'double'
   88 |         public double nextDouble()
      |               ^~~~~~~
      |               :
a.cc:92:2: error: expected ';' after class definition
   92 | }
      |  ^
      |  ;
a.cc: In constructor 'Scanner::Scanner()':
a.cc:64:17: error: 's' was not declared in this scope
   64 |                 s = new string[0];
      |                 ^
a.cc:64:25: error: 'string' does not name a type
   64 |                 s = new string[0];
      |                         ^~~~~~
a.cc: In member function 'int Scanner::nextInt()':
a.cc:80:24: error: expected primary-expression before 'int'
   80 |                 return int.Parse(next());
      |                        ^~~
a.cc:80:24: error: expected ';' before 'int'
a.cc:80:27: error: expected unqualified-id before '.' token
   80 |                 return int.Parse(next());
      |                           ^
a.cc: In member function 'long int Scanner::nextLong()':
a.cc:85:24: error: expected primary-expression before 'long'
   85 |                 return long.Parse(next());
      |                        ^~~~
a.cc:85:24: error: expected ';' before 'long'
a.cc:85:28: error: expected unqualified-id before '.' token
   85 |                 return long.Parse(next());
      |                            ^
a.cc: In member function 'double Scanner::nextDouble()':
a.cc:90:24: error: expected primary-expression before 'double'
   90 |                 return double.Parse(next());
      |                        ^~~~~~
a.cc:90:24: error: expected ';' before 'double'
a.cc:90:30: error: expected unqualified-id before '.' token
   90 |                 return double.Parse(next());
      |                              ^