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: Wrong Answer)

//============================================================================
// Name        : JOI.cpp
// Author      :
// Version     :
// Copyright   : Your copyright notice
// Description : Hello World in C++, Ansi-style
//============================================================================

#include <iostream>
#include <cstdio>
#include <string>
#include <algorithm>
#include <math.h>
#include <stdio.h>
#include <vector>
using namespace std;
typedef long long ll;
ll N;
int main() {
	cin>>N;

	for(int i=1;i<N;i++){
		if(i*i>N){
			cout<<(i-1)*(i-1)<<endl;
			break;
		}
	}
	return 0;
}