#include<string>
#include<vector>
#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<stack>
#include<queue>
#include<cmath>
#include<algorithm>
#include<list>
#include<set>
#include<map>
#include<cstring>
#include<sstream>
#include<cassert>
#define X first
#define Y second
#define pb push_back
#define rep(X,Y) for (int (X) = 0;(X) < (Y);++(X))
#define reps(X,S,Y) for (int (X) = S;(X) < (Y);++(X))
#define rrep(X,Y) for (int (X) = (Y)-1;(X) >=0;--(X))
#define repe(X,Y) for ((X) = 0;(X) < (Y);++(X))
#define peat(X,Y) for (;(X) < (Y);++(X))
#define all(X) (X).begin(),(X).end()
#define rall(X) (X).rbegin(),(X).rend()
#define eb emplace_back
#define UNIQUE(X) (X).erase(unique(all(X)),(X).end())

using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;

int main()
{
    ll s;
    cin >> s;
    
    for (ll i = 1; i < s; ++i) {
        if (i < 1000000 && s <= 3 * (i + 1000000) * (i + 1000000)) {
            cout << i << endl;
            return 0;
        }
        if (i >= 1000000 && 3*(i - 1000000)*(i - 1000000) <= s && s <= 3*(i + 1000000)*(i + 1000000)) {
            cout << i << endl;
            return 0;
        }
    }
    
    return 0;
}