111. Very simple problem



111. Very simple problem

time limit per test: 0.25 sec.
memory limit per test: 4096 KB

You are given natural number X. Find such maximum integer number that it square is not greater than X.

Input

Input file contains number X (1≤X≤10¹⁰⁰⁰).

Output

Write answer in output file.

Sample Input

16

Sample Output

4