>>> import datetime
>>> from date_checking import verificacio

---iniex
>>> l = []
>>> l.append((datetime.date (2023, 3, 20), datetime.date (2023, 3, 25)))
>>> l.append((datetime.date (2023, 3, 20), datetime.date (2023, 3, 20)))
>>> l.append((datetime.date (2023, 3, 20), datetime.date (2023, 3, 19)))
>>> l.append((datetime.date (2023, 3, 20), datetime.date (2023, 2, 15)))
>>> verificacio(l)
(2, -1)

---fiex
>>> l = []
>>> l.append((datetime.date (2023, 3, 20), datetime.date (2023, 3, 25)))
>>> l.append((datetime.date (2023, 3, 25), datetime.date (2023, 3, 30)))
>>> l.append((datetime.date (2023, 3, 20), datetime.date (2023, 3, 20)))
>>> l.append((datetime.date (2023, 3, 30), datetime.date (2023, 4, 1)))
>>> l.append((datetime.date (2023, 3, 30), datetime.date (2023, 4, 25)))
>>> verificacio(l)
(-1, -1)


>>> l = []
>>> verificacio(l)
(-1, -1)