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: Accepted)

#include <algorithm>
#include <array>
#include <bitset>
#include <cassert>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <iomanip>
#include <iostream>
#include <iterator>
#include <map>
#include <memory>
#include <numeric>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <sstream>
#include <unordered_map>
#include <vector>


#define INF 4000000000000000000LL
#define MOD 1000000007
#define ALL(x) std::begin(x), std::end(x)


int main(int argc, char** argv)
{
  std::cin.tie(0);
  std::ios_base::sync_with_stdio(0);

  std::cout << std::fixed << std::setprecision(6);
  std::cerr << std::fixed << std::setprecision(6);

  std::string S, T;

  std::cin >> S >> T;

  int c = 0;

  for (int i = 0, size = S.size(); i < size; i ++)
    if (S[i] != T[i])
      c ++;

  std::cout << c << std::endl;

  return 0;
}