[CCF CSP] 201803-1 jump jump

Problem description

　　 Recently, , This little game is popular all over the country , Loved by many players .
　　 The simplified one hop rule is as follows ： Each time the player jumps from the current box to the next box , If you don't jump to the next box, the game is over .
　　 If you jump on a square , But if you don't jump to the center of the box, you get 1 branch ; Jump to the center of the box , If the last score was 1 Points or if this is the first jump of the game, the score this time is 2 branch , Otherwise, this score is two points more than the last score （ That is, when you jump to the center of the box continuously , Total score +2,+4,+6,+8...）.
　　 Now let's give the whole process of one person jumping , Please find out his score in this game （ According to the rules of topic description ）.

Input format

　　 The input contains multiple numbers , Separate... With spaces , Every number is 1,2,0 One of ,1 It means that the jump jumped on the square but didn't jump to the center ,2 It means that this jump jumped on the square and jumped to the center of the square ,0 It means that this jump didn't jump on the box （ The game is over ）.

Output format

　　 Output an integer , Score for this game （ Under the rules of this question ）.

The sample input

1 1 2 2 2 1 1 2 2 0

Sample output

22

Data size and engagement

　　 For all profiling use cases , The number entered does not exceed 30 individual , Guarantee 0 Appears exactly once and is the last number .