14. (12 points) A natural number that satisfies the following two conditions is called a "lucky number": (1) Starting from the third digit from left to right, each digit is the difference between the two preceding digits (the larger number minus the smaller number); (2) No repeated digits. For example: 132, 871, 54132 are all "lucky numbers"; but 8918 (the digit "8" is repeated), 990 (the digit "9" is repeated) are not "lucky numbers". What is the second digit from left to right of the largest "lucky number"? $\qquad$
14. (12 points) A natural number that satisfies the following two conditions is called a "lucky number": (1) Starting from the third digit from left to right, each digit is the difference between the two preceding digits (the larger number minus the smaller number). (2) No repeated digits. For example: 132, 871, 54132 are all "lucky numbers"; but 8918 (the digit "8" is repeated), 990 (the digit "9" is repeated) are not "lucky numbers". What is the second digit from left to right of the largest "lucky number"?

【Solution】According to the problem, the largest digit starts with 9.
If it starts with 98, then the number is 98176;
If it starts with 97, then the number is 97253;
If it starts with 96, then the number is 963;
If it starts with 95, then the number is 954132;
If it starts with 94, then the number is 9451;
If it starts with 93, then the number is 936;
If it starts with 92, then the number is 9275;
If it starts with 91, then the number is 9187;
The largest number is 954132. It is easy to see that a "lucky number" cannot contain 0. If it were a 7-digit number, it would be impossible to achieve.
Therefore, the answer is: 5.