The first condition is that all the arrays in line f(i) are not equal. The first line is 1234...n, and the second line is also 1234...n, indicating one-to-one mapping.

The second condition is that m can be in f( 1), f(2)...f(m), corresponding to a table, that is, except 1, 2 is preceded by 2 (or its corresponding position), 3 is preceded by 3, 4 is preceded by 4 ... n.

The first question, if the second condition is met, the first space must be 2, and the last two are optional.

Secondly, you can make a list and try it. If the first cell is 1, then every subsequent cell is equal to the corresponding i. Therefore, the first cell is not 1, and f(i)=i has six solutions, that is, there are six i's corresponding to f(i), and * * has C6(9)=84 kinds (1 cannot correspond. So this blank is 84.