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)

// 2019/06/20
// AtCoder Beginner Contest 077 - B

#include <bits/stdc++.h>
using namespace std;

int main() {
    int n, wn, i, ans;
    cin >> n;
    i = 0;
    while(wn < n){
        i += 1;
        wn = i * i;
    }
    if(wn > n){
        ans = (i - 1) * (i - 1);
    } else {
        ans = wn;
    }
    cout << ans;
}