#include <bits/stdc++.h>
using namespace std;
#define MOD 998244353
#define ll long long
#define ull unsigned long long
#define ld long double
const int MAX_n = 1e5 + 5;
#define MAX_X 1000000
const int InF = 1e9; // for int
const ll INF = 1e18; // for ll

void solve()
{
    int n;
    cin>>n;
    vector<int>v;
    for(int i=1;i*i<=n;i++)
    {
        if((i*i)<=n)
        {
            v.push_back(i*i);
        }
        if((i*(i+1))<=n)
        {
            v.push_back((i*(i+1)));
        }
    }
    cout<<v.size()<<endl;

    
}

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);

    solve();
    return 0;
}