input: Write a python function to find the largest and second-largest numbers in a list of random integers.
  assert find_two_largest([10, 20, 15, 12, 30, 25, 18])== (30, 25)
  assert find_two_largest([1, 2, 3, 4, 5, 6, 7, 8, 9, 10])== (10, 9)
  assert find_two_largest([50, 30, 40, 20, 10])== (50, 40)
output: def find_two_largest(nums):
      if len(nums) < 2:
          raise ValueError("List must contain at least two elements.")
      
      first, second = float('-inf'), float('-inf')
      
      for num in nums:
          if num > first:
              second = first
              first = num
          elif num > second and num != first:
              second = num
      
      return (first, second)