#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define endl '\n'
#define yes cout << "YES" << endl
#define no cout << "NO" << endl
#ifdef LOCAL
#include "algo/debug.h"
#else
#define debug(...) 42
#endif
const double PI = acos(-1);
const ll MOD = 998244353;

void solve()
{
    // cout << fixed << setprecision(2);
    ll n,cnt=0,p=1;
    cin>>n;
    while(1){
        ll a=p*p;
        ll b=p*(p+1);
        if(a>n) break;
        cnt++;
        if(b<=n) cnt++;
        p++;
    }
    cout<<cnt<<endl;
}

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    // ll tstcs;
    // cin >> tstcs;
    // for (int t = 1; t <= tstcs; t++)
    {
        // cout << "Case " << t << ": ";
        solve();
    }
    return 0;
}