#include <bits/stdc++.h>
// clang-format off
using namespace std; using ll=long long; using ull=unsigned long long; using pll=pair<ll,ll>; const ll INF=4e18;
void print0(){}; template<typename H,typename... T> void print0(H h,T... t){cout<<h;print0(t...);}
void print(){print0("\n");}; template<typename H,typename... T>void print(H h,T... t){print0(h);if(sizeof...(T)>0)print0(" ");print(t...);}
void perr0(){}; template<typename H,typename... T> void perr0(H h,T... t){cerr<<h;perr0(t...);}
void perr(){perr0("\n");}; template<typename H,typename... T>void perr(H h,T... t){perr0(h);if(sizeof...(T)>0)perr0(" ");perr(t...);}
void ioinit() { cout<<fixed<<setprecision(15); cerr<<fixed<<setprecision(6); ios_base::sync_with_stdio(0); cin.tie(0); }
// clang-format on

int main() {
    ioinit();
    ll N;
    cin >> N;
    string S;
    cin >> S;

    set<pll> changed;
    bool nochange = false;
    for (ll i = 0; i < N - 1; i++) {
        bool cur = (S[i] == 'A');
        bool nxt = (S[i + 1] == 'A');
        if (cur && nxt) {
            changed.insert({i, i + 1});
        }
        if (cur && !nxt) {
            changed.insert({i, i});
        }
        if (!cur && nxt) {
            changed.insert({i + 1, i + 1});
        }
        if (!cur && !nxt) {
            nochange = true;
        }
    }
    ll ans = changed.size();
    if (nochange) ans++;
    print(ans);
    return 0;
}