int total(long h){

return h * (h+1) * (h+2) / 6;

}

int minimumBoxes(int n) {

//find the maxiumn height which total(height) <= n

//binary search

int left = 1, right = pow(6l*n, 1.0/3) ;

while(left <= right){

int mid = left + (right - left) / 2;

int t = total(mid);

if ( t == n ) return mid*(mid+1l)/2;

if ( t < n) left = mid + 1;

else right = mid - 1;

}

int height = right;

int remind = n - total(height);

int bottom = height * (height+1l)/2 ;

//cout << "n=" << n << ", height=" << height <<

// ", bottom = " << bottom << ", remind=" << remind << endl;

//find teh maxium h which sum(1..h) <= remind

//binary search

left = 1; right = sqrt(2*remind);

while ( left <= right) {

int mid = left + (right - left)/2;

int h = mid*(mid+1)/2;

if ( h == remind) return bottom + mid;

if ( h < remind) left = mid + 1;

else right = mid -1;

}

//cout << "left=" << left << ", right=" << right << endl;

return bottom + left;

}