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)

//77B
#include <bits/stdc++.h>
#define rep(i, n) for(int i=0; i<n; i++)
using namespace std;
int main(void){
    int n;
    cin >> n;
    for(int i=n; i>0; i--){
        if(sqrt(i) == floor(sqrt(i))){
            cout << i << endl;
            return 0;
        }
    }
}