266A

#include <iostream>
#include <string>
using namespace std;

int main()
{
	string stones;
	int n,count;
	while(cin>>n>>stones)
	{
		count=0;
		for(int i=0; i<stones.size()-1; ++i)
			if(stones[i]==stones[i+1])
				++count;
		cout<<count<<endl;
	}
	return 0;
}