8. On New Year's Eve, Father Frost gave the children the following task: using all nine digits from 1 to 9 once each, insert "+" or "-" between every two adjacent digits so that after performing the operations, all possible two-digit prime numbers can be obtained. Help the children complete this task. How many such numbers can be obtained
8. If we place only the "+" sign between the digits, we will get 45 after performing the operations. There are only 10 prime two-digit numbers less than 45. These numbers are $11,13,17,19,23,29,31,37,41,43$. They can be obtained as follows:
1) $1+2+3+4+5+6-8-9=11$
2) $1+2+3+4+5+6-7+8-9=13$
3) $1+2+3+4-5+6+7+8-9=17$
4) $1+2+3-4+5+6+7+8-9=19$
5) $1-2+3+4+5+6+7+8-9=23$
6) $1+2+3+4+5+6+7-8+9=29$;
7) $1+2+3+4+5+6-7+8+9=31$
8) $1+2+3-4+5+6+7+8+9=37$
9) $1-2+3+4+5+6+7+8+9=41$
10) $2-1+3+4+5+6+7+8+9=43$.