input: Write a python function to find the closest pair of points from a list of points.
  assert closestPair([(-2, -4), (0, 0), (-1, 1), (2,2), (3, 3), (-2,2), (4,4)], 7) == 1
  assert closestPair([(1, 2), (3, 4), (5, 6), (7, 8)], 4) == 8
  assert closestPair([(0, 0), (1, 1), (1, 0), (0, 1)], 4) == 1
output: def closestPair(points, n):
      import itertools
      import math
  
      def distance(p1, p2):
          return math.sqrt((p1[0] - p2[0]) ** 2 + (p1[1] - p2[1]) ** 2)
  
      min_dist = float('inf')
      closest_points = None
  
      for (p1, p2) in itertools.combinations(points, 2):
          dist = distance(p1, p2)
          if dist < min_dist:
              min_dist = dist
              closest_points = (p1, p2)
  
      return int(min_dist)