#include<bits/stdc++.h>
using namespace std;

/*#ifndef ONLINE_JUDGE
#include "DEBUG.h"
#define bug(...)           __f (#__VA_ARGS__, __VA_ARGS__)
#endif*/

#define first_in_out       ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
#define int                 long long int
#define double             long double
#define print(a)           for(auto x : a) cout << x << " ";
#define printpair(a)       for(auto x : a) cout << x.first << " " << x.second<<"\n";



void solve()
{

	int n;
	cin >> n;
	int cnt = 0;

	for (int i = 1; i <= n; i++)
	{
		if (1ll * i * i <= n)
			cnt++;
		if (1ll * i * (i + 1) <= n)
			cnt++;

	}

	cout << cnt << "\n";
}


int32_t main()
{
	first_in_out

	int t = 1;
	//cin >> t;

	while (t--)
		solve();

}