Metro roams in a city of 20 stations, Starting from Station number 0 to last station 19. It Stops at each station for 1 sec (neglect the time of station switching). A Guy daily waits at station number 11 for the train. Given n i,e current station no. at which metro is and its direction c, find the time he has to wait to catch up the train.
Example 1:
Input: n = 0, c = U
Output: 11
Explanation: Since train is at station number
0, so the guy has to wait 11 sec.
Example 2:
Input: n = 12, c = D
Output: 1
Explanation: Since train is at station number
12 and its direction is down it means the guy
has to wait for only 1 sec.

Your Task:
You don't need to read or print anything. Your task is to complete the function waiting_time() which takes n and c as input parameter and returns the time for which the guy has to wait.

Expected Time Complexity: O(1)
Expected Space Compelxity: O(1)
Constraints:
0 <= n <= 19
c € ['D', 'U']

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