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 pb push_back
#define M 100005
#define ll long long int
#define rep(i,n) for(int i=1;i<n;i++)
#define mp(a,b) make_pair(a,b)
#define gcd(a,b)    __gcd(a,b)
#define lcm(a,b) ((a)*((b)/gcd(a,b)))
using namespace std;
int main(){
	ll n;
	cin>>n;
	int i=sqrt(n);
	cout<<i*i<<endl;
return 0;
}