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Problem Statement

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.

Sample Input 1

cupofcoffee
cupofhottea

Sample Output 1

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.

Sample Input 2

abcde
bcdea

Sample Output 2

5

Sample Input 3

apple
apple

Sample Output 3

0

No operations may be needed to achieve the objective.