#include <bits/stdc++.h>
using namespace std;
using ch = char;
using ll = long long;
using ld = long double;
using db = double;
using st = string;
using vdb = vector<db>;
using vvdb = vector<vdb>;
using vl = vector<ll>;
using vvl = vector<vl>;
using vd = vector<ld>;
using vvd = vector<vd>;
using vs = vector<st>;
using vvs = vector<vs>;
using vc = vector<ch>;
using vvc = vector<vc>;
using vb = vector<bool>;
using vvb = vector<vb>;
const ll mod = 998244353;
const ll MOD = 1000000007;
using vp = vector<pair<ll,ll>>;
#define fi first
#define se second

int main(){
  ll N;
  cin>>N;
  st S;
  cin>>S;
  ll ans=1;
  ll a,b,c;
  ll f=0;
  if(S.at(0)=='A')
    c=0;
  else
    c=1;
  for(int i=1; i<N-1; i++){
    if(S.at(i)=='A')
      a=0;
    else
      a=1;
    if(S.at(i+1)=='A')
      b=0;
    else
      b=1;
    if(a==1&&b==1)
      f=1;
    if(a==0||b==0)
      ans++;
    if(b==1&&c==1)
      ans--;
    c=a;
  }
  if(f)
    ans++;
  cout<<ans<<endl;
}