#include <iostream>
#include <algorithm>
#include <vector>
#define forn(i,n) for(int i=0;i<(int)n;++i)
#define DBG(a) cerr<<#a<<" = "<<a<<endl
#define DBGA(a) cerr<<#a<<" = "<<a<<", ";
#define DBG2(a,b) do{DBGA(a)DBG(b);}while(0)
#define DBG3(a,b,c) do{DBGA(a)DBGA(b)DBG(c);}while(0)
#define DBG4(a,b,c,d) do{DBGA(a)DBGA(b)DBGA(c)DBG(d);}while(0)
#define SZ(v) (int)v.size()
#define ALL(v) v.begin(),v.end()
using namespace std;
template<typename T>
ostream &operator<<(ostream &os, vector<T> &v){
os<<"[";
forn(i,SZ(v)){
if(i) os<<", ";
os<<v[i];
}
os<<"]";
return os;
}
typedef long long ll;
const int MAXN = 200005;
int ft[2*MAXN];
void update(int i0, int v){
for(int i=i0+1;i<2*MAXN;i+=i&-i) ft[i]+=v;
}
int get(int i0){
int r=0;
for(int i=i0;i;i-=i&-i) r+=ft[i];
return r;
}
int get_sum(int i0, int i1){
return get(i1)-get(i0);
}
vector<int> a;
ll check(int k, vector<int> b){
int n = SZ(a);
rotate(b.begin(), b.begin()+k, b.end());
vector<pair<int,int>> rs;
forn(i,n){
int l = a[i], r = b[i];
if(l > r) swap(l, r);
rs.push_back({l, r});
rs.push_back({r, l});
}
sort(ALL(rs));
ll ret = 0;
for(auto x: rs){
if(x.first < x.second){
ret += get_sum(x.first, x.second);
update(x.second, +1);
} else{
update(x.first, -1);
}
}
return ret;
}
void solve(){
int n;
string s;
cin>>n>>s;
#ifdef LOCAL
a.clear();
#endif
vector<int> b;
forn(i,2*n){
if(s[i] == 'W') a.push_back(i);
else b.push_back(i);
}
int l=0, r=n+1;
while(r-l>1){
int m = (l+r)/2;
ll x = check(m-1, b), y = check(m, b);
if(y > x){
l = m;
} else{
r = m; // ???
}
}
ll ans = check(l, b);
cout<<ans<<"\n";
}
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
#ifdef LOCAL
freopen("input.in", "r", stdin);
int tcs;
cin>>tcs;
while(tcs--)
#endif
solve();
return 0;
}
