#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for(int i = 0; i< (int)(n); i++)
using ll = long long;
using ull = unsigned long long;
using vi = vector<int>;
ll INF = 2e18;
#define Yes cout << "Yes" << endl
#define No cout << "No" << endl
#define YN {cout<<"Yes"<<endl;}else{cout<<"No"<<endl;} // true → Yes false → No
// cout << fixed << setprecision(20);

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