input: Write a function to find the minimum index of a given number in a list.
  assert minIndex([3, 4, 1, 5, 2], 5) == 3
  assert minIndex([3, 4, 5, 5, 2], 5) == 2
  assert minIndex([3, 4, 1, 2, 2], 2) == 3
output: def minIndex(lst, num):
      try:
          return lst.index(num)
      except ValueError:
          return -1