#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
  #include "settings/debug.cpp"
#else
  #define Debug(...) void(0)
#endif
#define rep(i, n) for (int i = 0; i < (n); ++i)
using ll = long long;
using ull = unsigned long long;

int main() {
  int n;
  string s;
  cin >> n >> s;
  int ans = 0;
  rep(i, n - 1) {
    if (s.substr(i, 2) == "AA") ++ans;
  }
  rep(i, n) {
    if (s[i] == 'A' && ((i - 1 >= 0 && s[i - 1] == 'B') || (i + 1 < n && s[i + 1] == 'B'))) ++ans;
  }
  if (s.contains("BB")) ++ans;
  cout << ans << endl;
  return 0;
}