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