#include<bits/stdc++.h>

using namespace std;

int main () {
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
  int n;
  cin >> n;
  string s;
  cin >> s;
  int count = 0;
  for(int i = 0; i < s.size() - 1;i++) {
    if(s[i] == s[i + 1]) {
      count++;
    }
  }
  cout << count << endl;
}