#include <bits/stdc++.h>
using namespace std;
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  int n, count = 0;
  cin >> n;
  string s;
  cin >> s;
  for (int i = 0; i < n; i++) {
    if (s[i] == s[i - 1]) count++;
  }
  cout << count << endl;
}
