/*
 *   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);

ll bs(ll n) {
    ll l = 1, r = 2e9, res = 0;
    while (l <= r) {
        ll mid = (l + r) / 2;
        if (mid * (mid + 1) <= n) {
            res = mid;
            l = mid + 1;
        } else {
            r = mid - 1;
        }
    }
    return res;
}

void solve() {
    ll n;
    cin >> n;
    ll m1 = (ll) sqrt(n);
    ll m2 = bs(n);
    cout << m1 + m2 << endl;
}



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