To solve this problem, we need to convert a datetime string from the format YYYY/MM/DD HH:MM:SS to YYYY-MM-DD HH:MM:SS by replacing the slashes (/) in the date part with hyphens (-).

Approach

The key insight here is that the only slashes in the input string are in the date part. Therefore, we can directly replace all slashes in the entire string with hyphens. This approach is efficient and straightforward, as it avoids unnecessary splitting and joining of the string.

Solution Code

print(input().replace('/', '-'))

Explanation

1. Reading Input: The input string is read using input().
2. Replacing Slashes: The replace('/', '-') method is used to replace all occurrences of / with - in the input string.
3. Output: The modified string is printed, which now has hyphens in the date part and retains the original time format.

This solution is optimal with a time complexity of O(n) (where n is the length of the input string) since string replacement in Python processes each character once. It handles all valid inputs in the specified format correctly.

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