#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, r = 0;
  cin >> n;
  string s;
  cin >> s;
  for (int i = 0; i < n - 1; i++) {
    if (s[i] == s[i + 1]) r++;
  }
  cout << r;
  return 0;
}
