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++ (Clang 3.8.0) (judge verdict: Accepted)

#include <iostream>
#include <cstring>
#include <stdlib.h>
#include <vector>
#include <algorithm>
#include <cmath>
#include <stack>
#include <queue>
#include <math.h>

using namespace std;

int main()
{
    long int n;
    cin >> n;
    long int ans=1;
    while((ans*ans)<=n){
        ans++;
    }
    ans--;
    cout << ans*ans;
    
    return 0;
}