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 Rust (1.42.0) (judge verdict: Accepted)

fn main() {
  let s = gets();
  let t = gets();
  let cs = s.chars();
  let ds = t.chars();
  
  let mut cnt = 0;
  for (c, d) in cs.zip(ds) {
    if c != d {
      cnt += 1
    }
  };
  
  println!("{}", cnt);
}

// 今回使ってません
fn read<T: std::str::FromStr>() -> Vec<T> {
  gets().split_whitespace().filter_map(|s|s.parse().ok()).collect()
}

fn gets() -> String {
  let mut line = String::new();
  std::io::stdin().read_line(&mut line).ok();
  line.trim().to_string()
}