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)

#include <iostream>
#include <vector>
#include <algorithm>
#include <math.h>
using namespace std;

int main(){

    int N;
    cin >> N;
    
    double sq;
    double ans;
    int q;
    for(int i=N; i>=1; i--){
        sq = sqrt(i);
        ans = int(sq) * int(sq);
        if(i == ans){
            q = i;
            break;
        }
    }

    cout << q << endl;
    
    return 0;
}