Given are strings S and T. Consider changing S to T by repeating the operation below. Find the minimum number of operations required to do so.
Operation: Choose one character of S and replace it with a different character.

-----Constraints-----
- S and T have lengths between 1 and $2\times 10^5$ (inclusive).
- S and T consists of lowercase English letters.
- S and T have equal lengths.

-----Input-----
Input is given from Standard Input in the following format:
S
T

-----Output-----
Print the answer.

-----Sample Input-----
cupofcoffee
cupofhottea

-----Sample Output-----
4

We can achieve the objective in four operations, such as the following:
- First, replace the sixth character c with h.
- Second, replace the eighth character f with t.
- Third, replace the ninth character f with t.
- Fourth, replace the eleventh character e with a.

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