// Arup Guha
// 6/15/2023
// Solution to SIUCF CP Contest 2 Problem: Exam
// https://open.kattis.com/problems/exam

using namespace std;
#include <iostream>

int main() {

    // Read input.
    int n;
    string yours, mine;
    cin >> n >> yours >> mine;
    int total = yours.size();

    // Count same.
    int same = 0;
    for (int i=0; i<total; i++)
        if (yours[i] == mine[i])
            same++;

    // Best case is when other person was exactly right when they matched
    // you. Otherwise, you must miss the difference between how many were
    // same and the total they got right.
    cout << total - abs(n-same) << endl;

    return 0;
}