The Queen of Hearts has lost her tarts! She is sure that those knaves who have not eaten the tarts will tell her the truth and the guilty knave will tell lies. When questioned the five knaves declare:

Knave 1
One of us ate them.

Knave 2
Two of us ate them.

Knave 3
Three of us ate them.

Knave 4
Four of us ate them.

Knave 5
Five of us ate them.

How many of the knaves were honest?