This is a big integer challenge. You are given an integer which is a perfect square. It is composed of 40 or more digits. Compose a function which will find the exact square root of this integer.
square_root(152415787532388367501905199875019052100) ➞ 12345678901234567890
square_root(10203040506070809101112131413121110090807060504030201) ➞ 101010101010101010101010101