/// <summary>
/// Calculates the number of n-digit positive integers which are also an nth power
/// </summary>
static void P063()
{
Console.WriteLine((from i in Enumerable.Range(1, 9)
select(from j in Enumerable.Range(1, 25)
where BigInteger.Pow(i, j).ToString().Length == j select 1).Count()).Sum());
}