Task

Given two numbers x and n, calculate the nth root of x, e.g. r such that r^n = x. However, you're working with some kind of legacy API that doesn't contain a helpful function for this task (see end of the description).

Examples

root(4, 2);   // 2
root(8, 3);   // 2
root(256, 4); // 4
root(9, 2);   // 3

-- (~~~) stands for almost equal, given that we're using floating point numbers
root   4 2 ~~~ 2  
root   8 3 ~~~ 2
root 256 4 ~~~ 4
root   9 2 ~~~ 3

Disabled functions

The power function of your language (e.g. Math.pow in JavaScript, ** in Haskell) has been disabled. Good luck.