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

bool is_squere(long N) {
        long r = (long) floor(sqrt(N));
        return (r * r) == N;
}

int main() {
    int N;
    cin >> N;


    for(int i = N; i > 0; i--) {
        if(is_squere(i)) {
            cout << i << endl;
            return 0;
        }
    }
}
#define _GLIBCXX_DEBUG
#include <bits/stdc++.h>
using namespace std;
using ll = long long;

int main() {
  int n;
  cin >> n;
  
  int i = 1;
  while(1) {
    if(i*i>n) break;
    i++;
  }
  cout << (i-1)*(i-1) << endl;
  return 0;
}