#include<bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define endl '\n'
#define ll long long
#define vi vector<ll>
#define sz(x) (int)x.size()
#define all(x) x.begin(), x.end()
#define rep(i, a, b) for(ll i = (a); i < (b); i++)
#define print(v) for(auto e:v) cout<<e<<" "; cout<<endl;

void solve() {
    ll n;cin>>n;
    ll ki = sqrt(n);
    ll cnt = 0;
    rep(i,1,ki+1){
        ll ji = i*i;
        ll nts = i*(i+1);
        if(ji<=n) cnt++;
        if(nts<=n) cnt++;
    }
    cout<<cnt<<endl;
}


int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    ll t=1;//cin>>t;
    while(t--){
        solve();
    }
    return 0;
}