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

int main() {
    ll n;cin>>n;
    ll k = 1;
    ll ans = 1;
    bool f = false;
    for ( ; k*k <= n ; k++) {
        // cout<<k<<" ";
        if (k*(k+1) <= n || k*k <= n) {
            ans = k;
            if (k*(k+1) <= n) f = true; 
            else f = false;
        }
    }

    if (!f) {
        cout<<2*(ans-1)+1;
    } else {
        cout<<2*ans;
    }

    cout<<endl;
    return 0;
}