static void Main(string[] args)
{
#if DEBUG
var scanner = new IO.StreamScanner(File.Open("input.txt", FileMode.Open));
#else
var scanner = new IO.StreamScanner(Console.OpenStandardInput());
#endif
var a = scanner.Long();
var b = scanner.Long();
var c = scanner.Long();
var k = scanner.Long();
var ans = k % 2 == 0 ? a - b : b - a;
IO.Printer.Out.WriteLine(ans);
IO.Printer.Out.Flush();
}
static void Main(string[] args)
{
#if DEBUG
var scanner = new IO.StreamScanner(File.Open("input.txt", FileMode.Open));
#else
var scanner = new IO.StreamScanner(Console.OpenStandardInput());
#endif
var n = scanner.Integer();
var m = scanner.Integer();
var cakes = new List <Tuple <long, long, long> >();
for (int i = 0; i < n; i++)
{
cakes.Add(new Tuple <long, long, long>(scanner.Long(), scanner.Long(), scanner.Long()));
}
IO.Printer.Out.WriteLine(GetAns(n, m, cakes));
IO.Printer.Out.Flush();
}
static void Main(string[] args)
{
#if DEBUG
var scanner = new IO.StreamScanner(File.Open("input.txt", FileMode.Open));
#else
var scanner = new IO.StreamScanner(Console.OpenStandardInput());
#endif
var n = scanner.Integer();
var c = scanner.Long();
var x = new List <long>();
var v = new List <long>();
for (int i = 0; i < n; i++)
{
x.Add(scanner.Long());
v.Add(scanner.Long());
}
IO.Printer.Out.WriteLine(GetAns(n, c, x, v));
IO.Printer.Out.Flush();
}
