def merge_sort(a, b):
  ret = []
  while len(a)>0 and len(b)>0:
    if a[0] <= b[0]:
      ret.append(a[0])
      a.remove(a[0])  
    if a[0] >= b[0]:
      ret.append(b[0])
      b.remove(b[0])
  if len(a) == 0:
    ret += b
  if len(b) == 0:
    ret += a
  return ret


if __name__ == '__main__':
  a = [1,3,4,6,7,78,97,190]
  b = [2,5,6,8,10,12,14,16,18]
  print(merge_sort(a, b))

def merge_sort(a, b):
  ret = []
  i = j = 0
  while len(a) >= i + 1 and len(b) >= j + 1:
    if a[i] <= b[j]:
      ret.append(a[i])
      i += 1
    else:
      ret.append(b[j])
      j += 1
  if len(a) > i:
    ret += a[i:]
  if len(b) > j:
    ret += b[j:]
  return ret

if __name__ == '__main__':
  a = [1,3,4,6,7,78,97,190]
  b = [2,5,6,8,10,12,14,16,18]
  print(merge_sort(a, b))