#include<bits/stdc++.h>
using namespace std;
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
#define int long long
#define FOR(i,a) for(int i=0;i<(a);i++)
#define FORE(i,a,b) for(int i=(a);i<(b);i++)
#define sp <<' '<<
#define fi first
#define se second
#define pb push_back
typedef vector<int> vi;
typedef pair<int,int> pii;
typedef vector<pii> vii;
typedef vector<bool> vb;
typedef tree<int,null_type,less<int>,rb_tree_tag,tree_order_statistics_node_update> oset;
#define all(x) x.begin(),x.end()
#define cont(x) for(auto el:x) cout<<el<<' ';cout<<endl;
#define contp(x) for(auto el:x) cout<<el.fi<<'-'<<el.se<<' ';cout<<endl;
#define DEBUG(x) cout<<#x sp x<<endl;
#define carp(a,b) ((a%MOD)*(b%MOD))%MOD
#define topla(a,b) ((a%MOD)+(b%MOD))%MOD
#define mid (l+r)/2
const int MAXN=1e3+5;
const int MAXK=28;
const int MOD=1e9+7;
const int INF=1e18;
int n;
string s;
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(0);cout.tie(0);
//freopen("out.txt","w",stdout);
cin>>n;
cin>>s;
deque<int> bir,iki;
FOR(i,2*n){
if(s[i]=='W') bir.pb(i+1);
else iki.pb(i+1);
}
deque<int> uc,dort;
uc=bir;
dort=iki;
int res=0;
FOR(ind,n){
int bas=bir[ind];
//bir,iki matchli hal
//uc,dort sortlu hal
int ans=0;
FOR(i,n){
if(bir[i]<iki[i]){
int ara=iki[i]-bir[i]-1;
auto it1=lower_bound(all(uc),bir[i])-uc.begin();
auto it2=upper_bound(all(uc),iki[i])-uc.begin();
int tane=it2-it1-1;
//ara tane sayıdan "tane" kadarı whitemış
int a,b,c,d;
a=tane;b=ara-a;
ara=2*n-2-ara;
c=n-tane-1;d=ara-c;
ans+=min(a,d)+min(b,c);
}
else{
int ara=bir[i]-iki[i]-1;
auto it1=lower_bound(all(dort),iki[i])-dort.begin();
auto it2=upper_bound(all(dort),bir[i])-dort.begin();
int tane=it2-it1-1;
//ara tane sayıdan "tane" kadarı whitemış
int a,b,c,d;
a=tane;b=ara-a;
ara=2*n-2-ara;
c=n-tane-1;d=ara-c;
ans+=min(a,d)+min(b,c);
}
}
res=max(res,ans/2);
int deg=iki.front();
iki.pop_front();
iki.pb(deg);
}
cout<<res<<endl;
}
