#include<bits/stdc++.h> using namespace std; long ikun(long x)//劈荆成王，伴kun远航 {long n=1,s=0,y=0; while(s<=x) { s=s+pow(n,2); if(s>x) break; else {y++;n++;} } return y; } int main() { long a; cin>>a; cout<<ikun(a); }