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 <bits/stdc++.h>
#define rep(i,n) for (int i = 0; i < (n); ++i)
const int INF = 2147483647;//int max
const int MOD = 1000000007;
using namespace std;
using ll = long long;
using P = pair<int,int>;


int main() {
    ll n;
    cin >> n;
    ll x = 1;
    if(n == x){
        cout << x << endl;
        return 0;
    }
    while (1){
        if(x*x > n){
            cout << fixed << setprecision(0) << pow(x-1,2) << endl;
            return 0;
        }else{
            x++;
        }
    }
  
    return 0;
}
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