#include <bits/stdc++.h>

using namespace std;

#define IO ios_base::sync_with_stdio(0);cin.tie(0);
#define endl '\n'

int main() {
    IO;
    int n; cin >> n;
    string s; cin >> s;
    int res = 0;
    bool check = false;
    for (int i = 0; i < (int)s.size() - 1; ++i)
        if (s[i] == 'B' && s[i + 1] == 'B') check = true;
        else if (s[i] == 'A' && s[i + 1] == 'A' || s[i] == 'B' && s[i + 1] == 'A') ++res;
        else if (i == 0 || s[i - 1] == 'A') ++res;
        
    cout << res + check << endl;

    return 0;
}