#include <bits/stdc++.h>
typedef long long ll;
#define INF 1000000000
#define MOD 1000000007
using namespace std;
int main(void){
    ll n;
    cin>>n;
    int r=ceil(sqrt(n/3));
    if(r==0){
        cout<<1<<endl;
    }else{
        cout<<r<<endl;
    }
    return 0;
}