/*
 *   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;
    ll m = (ll) sqrt(n);
    ll c = m;
    for (ll a = 1; a <= m; a++) {
        ll v = a * (a + 1);
        if (v <= n) c++;
    }
    cout << c << endl;
}


int main() {
    saklan
    #ifndef ONLINE_JUDGE
        freopen("input.txt", "r", stdin);
    #endif
    solve();
    return 0;
}