Problem:
Score : 200 points

Problem Statement

Find the largest square number not exceeding N. Here, a square number is an integer that can be represented as the square of an integer.

Constraints

1 \leq N \leq 10^9

N is an integer.

Input

Input is given from Standard Input in the following format:

N

Output

Print the largest square number not exceeding N.

Sample Input 1

10

Sample Output 1

9

10 is not square, but 9 = 3 × 3 is. Thus, we print 9.

Sample Input 2

81

Sample Output 2

81

Sample Input 3

271828182

Sample Output 3

271821169

Solution in C++14 (GCC 5.4.1) (judge verdict: Accepted)

/*
title:

url:
*/

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <algorithm>
#include <functional>
#include <queue>
#include <limits>
#include <string>
#include <utility>
#include <cstring>
#include <map>
#include <cmath>
#include <iterator>

using namespace std;

#define rep(i, n) for (int i = 0; i < (n); i++)
#define INF 1000000007

typedef pair<int, int> pint;
typedef long long ll;

int main()
{
    int n;
    cin >> n;
    cout << (int)sqrt(n) * (int)sqrt(n) << endl;
}