Problem:
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.

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.

Solution in Lua (LuaJIT 2.1.0) (judge verdict: Runtime Error)

local S, T = io.read("*l", "*l")

local count = 0
--[[ パターン1
for i = 1, S:len() do
	if S:sub(i, i) ~= T:sub(i, i) then
		count = count + 1
	end
end
--]]
---[[ パターン2
local S_byte_s, T_byte_s = {}, {T:byte(1, -1)}
for i = 1, S:len() do
	S_byte_s[i] = S:byte(i)
	T_byte_s[i] = T:byte(i)
end

for i = 1, S:len() do
	if S_byte_s[i] ~= T_byte_s[i] then
		count = count + 1
	end
end
--]]
print(count)