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)


// Problem : B - Minor Change
// Contest : AtCoder - AtCoder Beginner Contest 172
// URL : https://atcoder.jp/contests/abc172/tasks/abc172_b
// Memory Limit : 1024 MB
// Time Limit : 2000 ms
// Powered by CP Editor (https://github.com/cpeditor/cpeditor)

#include<bits/stdc++.h>
#define int long long
#define db double
#define mod 1000000007
#define pb push_back
#define pp pair<int,int>
#define rep(i,a,b) for(int i=a;i<b;i++)
#define repe(i,a,b) for(int i=a;i<=b;i++)
#define repr(i,a,b) for(int i=b;i>=a;i--)
#define maxn 100005
#define ss second
#define ff first
#define all(a) a.begin(),a.end()
#define lb lower_bound
#define ub uppper_bound
using namespace std;
int inv(int a, int b){
 return 1<a ? b - inv(b%a,a)*b/a : 1;
}
void solve()
{
	string s,t;
	cin >> s >> t;
	int ans=0;
	rep(i,0,s.size())
	{
		if(s[i] != t[i])
		ans++;
	}
	cout << ans;
}
signed main()
{
	ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    int t=1;
    //cin >> t;
    while(t--)
    solve();
    return 0;
}