#include <bits/stdc++.h>
//#include <atcoder/all>
using namespace std;
//using namespace atcoder;
using ll = long long;
using vll = vector<ll>;
using vvll = vector<vll>;
using vvvll = vector<vvll>;
using vvvvll = vector<vvvll>;
using vb = vector<bool>;
using vvb = vector<vb>;
using vvvb = vector<vvb>;
using vvvvb = vector<vvvb>;
using vd = vector<double>;
using vvd = vector<vd>;
using vvvd = vector<vvd>;
#define all(A) A.begin(),A.end()
#define ALL(A) A.begin(),A.end()
#define rep(i, n) for (ll i = 0; i < (ll) (n); i++)
using pqr = priority_queue<pair<ll, ll>, vector<pair<ll, ll>>, greater<pair<ll, ll>>>;

template<class T>
bool chmax(T& p, T q, bool C = 1) {
    if (C == 0 && p == q) {
        return 1;
    }
    if (p < q) {
        p = q;
        return 1;
    }
    else {
        return 0;
    }
}

template<class T>
bool chmin(T& p, T q, bool C = 1) {
    if (C == 0 && p == q) {
        return 1;
    }
    if (p > q) {
        p = q;
        return 1;
    }
    else {
        return 0;
    }
}

ll gcd(ll(a), ll(b)) {
    if (b == 0)return a;
    ll c = a;
    while (a % b != 0) {
        c = a % b;
        a = b;
        b = c;
    }
    return b;
}


vector<vector<pair<ll,pair<ll,ll>>>> G;
vll D;
vector<bool> seen;

void dfs(ll n){
    seen[n]=1;
    for(auto v:G[n]){
        if(seen[v.first])continue;
        if(v.second.second==1){
            D[v.second.first]=1;
        }
        else D[v.second.first]=0;
        dfs(v.first);
    }
    return;
}

int main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);

    ll N;
    cin>>N;
    string S;
    cin>>S;
    ll an=0;
    ll b=0;
    rep(i,N-1){
        if(S[i]=='A'&&S[i+1]=='A'){
            an++;   
        }
        else if(S[i]=='A'&&S[i+1]=='B')an++;
        else if(S[i]=='B'&&S[i+1]=='A'){
            if(i!=N-1&&S[i+2]!='B')an++;
        }
        else b++;
        
    }
    cout<<(an)+(b>0)<<endl;
}