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