533. Dice Tower

Time limit per test: 1 second(s)
Memory limit: 262144 kilobytes
input: standard
output: standard

Polycarp loves not only to play games, but to invent ones as well. He has recently been presented with a board game which also had lots of dice. Polycarp quickly noticed an interesting phenomenon: the sum of dots on any two opposite sides equals 7.

The dice

An unfolded die
Polycarp invented the following game. He asks somebody to tell a positive integer n and then he constructs a dice tower putting the dice one on another one. A tower is constructed like that: Polycarp puts a die on the table and then (if he wants) he adds more dice, each time stacking a new die on the top of the tower. The dice in the tower are aligned by their edges so that they form a perfect rectangular parallelepiped. The parallelepiped's height equals the number of dice in the tower and two other dimensions equal 1 (if we accept that a die's side is equal to 1).

An example of a tower whose height equals 3
Polycarp's aim is to build a tower of minimum height given that the sum of points on all its outer surface should equal the given number n (outer surface: the side surface, the top and bottom faces).

Write a program that would determine the minimum number of dice in the required tower by the given number n. Polycarp can construct any towers whose height equals 1 or more.

The only input line contains integer n (1 ≤ n ≤ 106).

Print the only integer — the number of dice in the required tower. If no such tower exists, print

sample input
sample output

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sample output