#include <iostream>

using namespace std;

int main() {
    int n;
    cin >> n;

    char answer[n];

    //get input
    for(int i=0; i<n; i++) {
        cin >> answer[i];
    }

    int count = 0;

    for(int i=0; i<n; i++) {
        char c;
        cin >> c;
        if(c == answer[i]) {
            count++;
        }
    }

    cout << count;

    return 0;
}