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 C (Clang 10.0.0) (judge verdict: Accepted)

#include<stdio.h>
#include<string.h>
int main(void){
  int i,x;
  int a=0;
  char s[200001];
  char t[200001];
  
  scanf("%s",s);
  scanf("%s",t);
  
  x = strlen(s);
  
  for(i=0;i<x;i++){
   if(s[i]==t[i]){
    a++; 
   }
  }
  
  printf("%d",x-a);
 return 0; 
}