# Given a number n, find out a placement of *n queens* on an nxn chessboard such that they don’t attack each other.
# Given n (n <= 1000) and S integers, find out a permutation p such that <tex>1 * p[1] + 2 * p[2] + .. + n * p[n] = S</tex>.
# 2n knights have to sit around a roundtable. Each knight is friends with n + 1 other knights. Find a seating arrangement such that each knight is placed between two friends.

# Climb my dick suckers.

# Given two line segments in 3d space find the minimum distance between them.
# A party of n people is too large and has to be split to two tables. Given that each of the people has at most three enemies in the group, find a seating arrangement such that each person sits at a table with at most one of his enemies.
# Given a set A of n black points and a set B of n white points (no three points are collinear), join each point in A with one point in B respectively such that no two segments will intersect.