#include <bits/stdc++.h>
using namespace std;

int n, m = 1;
string s;
bool f;

int main() {    
    cin >> n >> s;
    
    for (int i = 1; i < n - 1; i++) {
        if (s[i - 1] == 'A' || s[i + 1] == 'A') {
            if (s[i] == 'B' && s[i + 1] == 'B') {
                if (!f) {
                    m++;
                    f = 1;
                }
            }
            else
                m++;
        }
    }

    cout << m << endl;
}