/*
tetration
tetration(a,n)=a^a^⋅⋅⋅^a (n times).
Very quickly, Anthony becomes interested in infinite tetrations,
namely
tetration(a,∞)=a^a^⋅⋅⋅∞ times.
Anthony wonders, given an arbitrary real number N, what is the
solution to tetration(a,∞)=N? Unable to figure it out, Anthony has
asked you to write a program to help him!
Here’s a fun fact: A solution only exists for 1/e≤N≤e.
Input
The first line of input contains one real number N, 0.36788≤N≤2.718281.
Output
Output a single line containing a real number a, such that
tetration(a,∞) =N. Your answer will be considered correct if its
absolute or relative error doesn’t exceed 1e−5.
*/
#include
#include
int main() {
double N{ 0 };
std::cin >> N;
std::cout << pow(N,1/N);
}