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: Wrong Answer)

use proconio::input;

pub fn calc(s: Vec<char>, t: Vec<char>) -> u16 {

    let len = s.len();
    let mut ans = 0;
    for i in 0 .. len {
        if s[i] != t[i] { ans += 1 };
    }
    ans
}

     
fn main() {
    input! {
        s: String,
        t: String,
    }
    let s: Vec<char> = s.chars().collect();
    let t: Vec<char> = t.chars().collect();
 
    let result = calc(s, t);
    println!("{}", result);
}