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: Runtime Error)

#include<stdio.h>
int main(void){
  int i,ans=0;
  char S[20000],T[20000];
  scanf("%s",S);
  scanf("%s",T);
  for(i=0;i<20000;i++){
    if(S[i]==NULL)break;
    if(S[i]!=T[i])ans+=1;
  }
  printf("%d\n",ans);
  return 0;
}