#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); i++)
using namespace std;
typedef long long ll;

int main(){
    cin.tie(0);
    ios::sync_with_stdio(0);
    
    int N; string S; cin >> N >> S;
    int BB = 0, AA = 0, A = 0;
    rep(i,N-1) {
        if(S.substr(i, 2) == "BB") BB = 1;
        if(S.substr(i, 2) == "AA") AA++;
    }

    rep(i,N) if(S[i] == 'A') {
        int ok = 0;
        ok |= 0 <= i - 1 && S[i - 1] == 'B';
        ok |= i + 1 < N  && S[i + 1] == 'B';
        A += ok;
    }
    cout << BB + AA + A << endl;
}