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)

#include <bits/stdc++.h>

using namespace std;
int main() {
  int n;
  cin >> n;
  int result = 0;
  for (int i = 1; i < n / 2; i++) {
    if (i * i > n) {
      result = i - 1;
      break;
    }
  }
  if (result == 1) {
    cout << result << endl;
    return 0;
  }
  cout << result * result << endl;
  return 0;
}