It is a custom of five good friends that they wear a different tie each day, each one the one they wore the longest ago. Each of them has at least two ties, but none of them has a dozen. None of them has two ties of the same color, and there are no two of them who have the same number of ties. We have the following data from the last month of last year:

1. On December 1, Aladár wore a blue, Bandi and Feri wore red, Pista wore green, and Géza wore a yellow tie.
2. On December 19, Pista wore green, Géza wore yellow, Feri wore blue, and the other two wore red ties.
3. On December 23, Pista wore a white tie, and on December 26, he wore a yellow tie.
4. The colors of the ties worn on December 11 were: yellow, red, blue, green, and white.
5. On New Year's Eve, all five wore ties of the same color as on December 1.

Question: What tie did Bandi wear on January 1 of this year?
At Christmas, or 30 days later, each good friend's December 1st worn scarf came up again, so the number of scarves each of them has is a divisor of 30. On the other hand, only the divisors of 30 that are greater than 1 and less than 12 are relevant, which are: $2, 3, 5, 6, 10$, and their number matches the number of boys, so these five numbers represent the number of scarves each of the five boys has.

Pista, Géza, and Bandi's number of scarves is also a divisor of 18, because they wore the same colored, i.e., the same scarf on the 19th as on the 1st, so their number of scarves is 2, 3, 6 in some order, these are the common divisors of 30 and 18 between 1 and 12. We read that Pista has 3 different colored scarves, but on the 26th, he wore a different scarf than on the 23rd, so he has 6 scarves.

Therefore, Aladár and Feri's number of scarves is 5 and 10 in some order, so on the 11th, both wore the same scarf they wore on the 1st, the blue and red ones.

Thus, the December 11th scarves of Bandi, Géza, and Pista are yellow, green, and white. The white scarf was Pista's, because we know he has 6 scarves, and 12 days later, on the 23rd, he wore a white scarf.

One of Bandi and Géza has 2 scarves, the other has 3, so 10 days later, on December 11th, one of them wore the scarf they wore on the 1st, the other did not. Their initial colors were red and yellow, the 11th ones were yellow and green; only yellow matches, which according to the initial data is Géza's, so he has 2 scarves, Bandi has 3, and on the 11th, he wore the green scarf.

From December 11th to January 1st, 21 days pass, which is a multiple of 3, so Bandi wore his December 11th scarf, the green one, on January 1st as well.