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: Wrong Answer)

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

int main()
{
    char S[1000],T[1000];
    fgets(S,1000,stdin);
    fgets(T,1000,stdin);
    int l,m,i,j,c=0;
    l=strlen(S);
    m=strlen(T);
    if(l==m)
    {
        
         for(i=0;i<=l;i++)
    {
        if(S[i]!=T[i])
        {
            c++;
        }
    }
    }
    else{
        printf(" ");
    }
    printf("%d",c);
   
    

    return 0;
}