/// Banu Denis - dp
#include <bits/stdc++.h>

using namespace std;
#define ll long long
#define ld long double
#define ull unsigned long long
#define pii pair<int,int>
#define MOD 1000000007
#define zeros(x) x&(x-1)^x
#define fi first
#define se second
#define NMAX 500005
const long double PI = acos(-1);

int n,t, dp[2][4];
string s;

int main(){
  ios::sync_with_stdio(false);
  cin >> t;
  while (t--) {
    cin >> n;
    cin >> s;
    memset(dp,0,sizeof(dp));
    int crt = 1;
    for (int i=0;i<s.size();i++) {
      crt = (crt^1);
      if (s[i] == '0') {
        dp[crt][0] = max(dp[crt^1][0] + 1, dp[crt^1][2] + 1);
        dp[crt][1] = dp[crt^1][1];
        dp[crt][2] = max(dp[crt^1][3] + 1, dp[crt^1][2]);
        dp[crt][3] = dp[crt^1][3];
      } else {
        dp[crt][0] = dp[crt^1][0];  
        dp[crt][1] = max(dp[crt^1][0] + 1, dp[crt^1][1]);
        dp[crt][2] = dp[crt^1][2];
        dp[crt][3] = max(dp[crt^1][3] + 1, dp[crt^1][1] + 1);
      }
    }

    cout << n - max({dp[crt][0], dp[crt][1], dp[crt][2], dp[crt][3]}) << '\n';
  }

  return 0;
}