/// Gheorghies Alexandru - greedy solution
#include<bits/stdc++.h>

using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<ll,ll> pll;
typedef pair<ld,ld> pld;

const ll LGMAX=20,NMAX=3e5+5;


void tc(){
    ll n,ans=0,len=0;
    string s;
    cin>>n>>s;
    for(ll i=0;i<n;i++){
        if(i && s[i]!=s[i-1]) len++;
        else{
            ans+=(len+1)/3;
            len=0;
        }
    }
    ans+=(len+1)/3;
    cout<<ans<<'\n';
}
int main()
{
    #ifndef ONLINE_JUDGE
        freopen("in.txt","r",stdin);
        freopen("out.txt","w",stdout);
    #endif // ONLINE_JUDGE
    ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
    ll t; cin>>t; while(t--)
        tc();
    return 0;
}