9. Teacher Shi distributed cards with the numbers $1$, $2$, $3$, and $4$ to Jia, Yi, Bing, and Ding, one card each. The following conversation then took place:
Jia to Yi: Your card number is 4; Yi to Bing: Your card number is 3;
Bing to Ding: Your card number is 2; Ding to Jia: Your card number is 1.
Teacher Shi noticed: People with cards of the same parity (odd or even) always told the truth to each other, while people with cards of different parity always lied to each other. Additionally, the sum of the numbers on Jia's and Ding's cards is less than the sum of the numbers on Yi's and Bing's cards.
What is the four-digit number formed by the numbers on Jia, Yi, Bing, and Ding's cards in order? $\qquad$
$2341$