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