#include <iostream>

using namespace std;

const int N = 10010;

char res[N], ans[N];

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

    for (int i = 1; i <= n; i ++) cin >> res[i];
    for (int i = 1; i <= n; i ++) cin >> ans[i];

    int cnt = 0;
    for (int i = 1; i <= n; i ++)
        if (res[i] == ans[i]) cnt ++;
    cout << cnt << endl;

    return 0;
}