void Solve(StreamScanner ss, StreamWriter sw)
{
//---------------------------------
var N = ss.Next(int.Parse);
var A = ss.Next(long.Parse, N).OrderBy(x => x).ToArray();
for (var i = 0; i < N; i++)
{
if (A[i] == (N % 2 == 0 ? i + 1 - i % 2 : i + i % 2))
{
continue;
}
sw.WriteLine(0);
return;
}
sw.WriteLine(new ModInt(2).Pow(N / 2));
//---------------------------------
}
