#include <bits/stdc++.h>
using namespace std;
using namespace chrono;
#if __has_include(<atcoder/all>)
#include <atcoder/all>
using namespace atcoder;
#endif

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

    set<pair<int, int>> st;

    int ans = 0;

    for (int i = 0; i + 1 < n; i++) {
        if (s[i] == 'A' && s[i + 1] == 'A') {
            if (st.find({i, i + 1}) == st.end()) {
                ans++;
                st.emplace(i, i + 1);
            }
        } else if (s[i] == 'A') {
            if (st.find({i, -1}) == st.end()) {
                ans++;
                st.emplace(i, -1);
            }
        } else if (s[i + 1] == 'A') {
            if (st.find({i + 1, -1}) == st.end()) {
                ans++;
                st.emplace(i + 1, -1);
            }
        } else {
            if (st.find({-1, -1}) == st.end()) {
                ans++;
                st.emplace(-1, -1);
            }
        }
    }

    cout << ans << endl;

    return 0;
}