【Question 12】  
Use $1,2,3,4,5$ to form a five-digit number, such that the difference between any two adjacent digits is at least 2. How many such five-digit numbers are there? $\qquad$个.
【Analysis and Solution】
1 starting with 2: 13524, 14253; then there are also 2 starting with 5;
2 starting with 3: $24135, 24153, 25314$; then there are 3 starting with 4;
3 starting with 4: $31425, 31524, 35241, 35142$; there are 14 such five-digit numbers.