#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #define mp make_pair #define pb push_back #define all(x) (x).begin(),(x).end() #define YES() printf("YES\n") #define NO() printf("NO\n") using namespace std; #define int long long //typedef long long ll; typedef unsigned long long ull; typedef vector vb; typedef vector vi; typedef vector vvb; typedef vector vvi; typedef pair P; const int INF=1e+9; const double EPS=1e-9; const int MOD=1000000007; const int dx[]={1,0,-1,0},dy[]={0,-1,0,1}; signed main(){ int n; cin >> n; cout << (int)sqrt(n / 3) << endl; return 0; }