Madadia is split, like other countries, into cities, towns and villages. Some are large and some are small. Postman Patel delivers the mail in the village of "Lardville".

Now Lardville is so small there is only one street with only ten houses, numbered from 1 to 10.

In a certain week, Patel did not deliver any mail at two houses in the village; at the other houses he delivered mail three times each. Each working day he delivered mail at exactly four houses.

The sums of the house numbers where he delivered mail were:
on Monday: 18
on Tuesday: 12
on Wednesday: 23
on Thursday: 19
on Friday: 32
on Saturday: 25
on Sunday: he never works just in case any murder suspects try to use this as an excuse.

Can you work out which two houses received no mail this week?