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 (GCC 9.2.1) (judge verdict: Runtime Error)

//
//  main.c
//  Minor Change
//
//  Created by k19031kk on 2020/06/27.
//  Copyright © 2020 AIT. All rights reserved.
//

#include <stdio.h>
#include <string.h>

int main(int argc, const char * argv[]) {
    
    int ret,ret1;
    
    char sentence1[254];
    char sentence2[254];
    
    int count = 0;
    
    ret = scanf("%s",sentence1);
    
    if(ret == EOF){
        return -1;
    }
    
    ret1 = scanf("%s",sentence2);
    
    if(ret1 == EOF){
        return -1;
    }
    
    int len = (int) strlen(sentence1);
    int len1 = (int) strlen(sentence2);
    if(len != len1){
        return -1;
    }
    
    for(int i=0;i<len;i++){
        if(!(sentence1[i]>= 'a') && (sentence1[i]<='z')){
            return -1;
        }
        
        if(!(sentence2[i]>= 'a') && (sentence2[i]<='z')){
            return -1;
        }
    }
    
    
    for(int i=0;i<len;i++){
        
        if(sentence1[i] != sentence2[i]){
            count++;
        }
    }
    
    printf("%d\n",count);
    return 0;
}