#pragma GCC optimize("Ofast")
#include <iostream>
#include <math.h>
#include <cstdint>
using namespace std;
#ifndef ONLINE_JUDGE
#define debug(x) cerr << #x << " = " << x << endl
#else
#define debug(x)
#endif

using ll = long long;
/*
a(a-1) = n
=> a^2 - a - n = 0
x1 = (-1 + sqrt(b*b - 4 *a*c))/2*a
*/
void Solve()
{
    ll n;
    cin >> n;
    cout << floor(sqrt(n)) + int((floor(sqrt(1 + n*4)) - 1)/2) << endl;
}

int32_t main()
{
    ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);
    ll t = 1;
    // cin >> t;
    while (t--)
        Solve();
    return 0;
}