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>
using namespace std;
#define all(vec) vec.begin(),vec.end()
typedef long long int ll;
typedef pair<ll,ll> P;
const ll MOD=1234567;
const ll INF=1000000010;
const ll LINF=1000000000000000010LL;
const int MAX=500010;
const double EPS=1e-3;
int dx[4]={0,1,0,1};
int dy[4]={0,0,1,1};
int main(){
    int n;cin>>n;
    int s=sqrt(n);
    cout<<s*s<<endl;
    return 0;
}