#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


int main() {
    int Q, len, counter;
    string str;
    cin >> Q;
    for (int i = 0; i < Q; i++){
        counter = 0;
        cin >> len >> str;
        for (int j = 1; j < len + 1; j++){
            if (str[j] == str[j-1]) { counter++; }
        }
        cout << counter << endl;
    }
    return 0;
}