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