B - Minor Change

Score : $200$ points

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.

Input

Input is given from Standard Input in the following format:

$S$

$T$

Output

Print the answer.

cupofcoffee
cupofhottea

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.

abcde
bcdea

5

apple
apple

0

No operations may be needed to achieve the objective.