#include<iostream> 
#include<cstring>
#include<stack>
using namespace std;
int main() {
	freopen("game.in","r",stdin);
	freopen("game.out","w",stdout);
	int n;
	int sum = 0;
	cin>>n;
	string s;
	cin>>s;
	for(int i = 0;i<n;i++){
		if(st.empty() != 0){
			if(st.top() == s[i]){
				sum++;
				st.pop(); 
			}else{
				st.push(s[i]);
			}
		}else{
			st.push(s[i]);
		}			
	}	
	cout<<sum;
	return 0;
}