Very simple problem

Problem Description

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≤10^1000).

Output

Write answer in output file.

Sample Input

16

Sample Output

4

Solution

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if __name__ == '__main__':

    n = int(input())
    x = n
    y = (x + 1) // 2
    while y < x:
        x = y
        y = (x + n // x) // 2

    print(x)