/*
* BISMILLAHIR RAHMANIR RAHIM
* ==========================
*
* Submitted By: SAKLAN
* North East University Bangladesh
*/
#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ld long double
#define cinv(v) for(auto &i:v) cin >> i;
#define vi vector<int>
#define vii vector<ll>
#define mod 1000000000
#define cout(v) for(auto e:v) cout << e << sp;
#define srt(v) sort(v.begin(),v.end())
#define rsrt(v) sort(v.rbegin(),v.rend())
#define yes cout<<"YES\n"
#define no cout<<"NO\n"
#define endl '\n'
#define start long long t; cin >> t; while(t--)
#define saklan ios::sync_with_stdio(0); cin.tie(0);
void solve() {
ll n;
cin >> n;
unordered_set<ll> s;
for (ll a = 1; ; a++) {
ll x = a * a;
if (x > n) break;
s.insert(x);
if (a * (a + 1) <= n)
s.insert(a * (a + 1));
}
cout << s.size() << endl;
}
int main() {
saklan
#ifndef ONLINE_JUDGE
freopen("input.txt", "r", stdin);
#endif
solve();
return 0;
}