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 Python (3.8.2) (judge verdict: Runtime Error)

def minchange(s,t):
  m=len(s)
  n=len(t)
  if n!=m:
    return -1
  cnt=[0]*256
  for i in range(n):
    cnt[ord(t[i])]+=1
  for i in range(n):
    cnt[ord(s[i])]-=1
  for i in range(256):
    if cnt[i]:
      return -1
  res=0
  i=n-1
  j=n-1
  while i>=0:
    while i>=0 and s[i]!=t[i]:
      i-=1
      res+=1
    if i>=0:
      i-=1
      j-=1
  return res
s=input()
t=int(input())
print(str(minchange(s,t))