#include <iostream>

using namespace std;

int n, cnt;
char s[10010], c;

int main()
{
    cin >> n;
    for (int i = 0; i < n; i ++ ) cin >> s[i];
    for (int i = 0; i < n; i ++ )
    {
        cin >> c;
        if (c == s[i]) cnt ++;
    }

    cout << cnt;

    return 0;
}