Christanio Ronaldo is a strange liar.
He lies on six days of the week, but on the seventh day he always tells the truth.
He made the following statements on three successive days:
Day 1: 'I lie on Monday and Tuesday.'
Day 2: 'Today, it's Thursday, Saturday, or Sunday.'
Day 3: 'I lie on Wednesday and Friday.'
On which day does Christanio Ronaldo tell the truth?