#include <iomanip>
#include <string>
#include <iostream>
#include <algorithm>
#include <math.h>
#include <cmath>
#include <queue>
#include <deque>
using namespace std;
typedef long long ll;
int arr[100005];
int main()
{
std::ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int n, idx = 0, idxArray = 0, cntr = 0;
string s1, s2;
cin >> n >> s1 >> s2;
if (s1 == s2)
{
cout << 0;
return 0;
}
for (int i = 0; i < s2.size(); i++)
{
if (s2[i] == s1[idx])idx++;
else if (s2[i] != s1[idx])
{
arr[idxArray] = i;
idxArray++;
idx++;
}
} // 0 1 2
for (int i = 0; i < idxArray; i++)// 1 2 5
{
if (arr[i + 1] - arr[i] > 1 && i != idxArray - 1) // 5-2 > 1
{
cntr++;
}
}
cntr++;
cout << cntr;
return 0;
}