#include<bits/stdc++.h>
using namespace std;
#ifndef BADGNU
#pragma GCC target("sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,avx2,tune=native")
#endif
#pragma GCC optimize("Ofast,unroll-loops,fast-math,O3")
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
#define ll long long
#define int ll
#define ld long double
#define y1 cheza
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
template<class T> using ordered_set = tree<T,null_type,less<T>,rb_tree_tag,tree_order_statistics_node_update>;
template<class T> using ordered_multiset = tree<T,null_type,less_equal<T>,rb_tree_tag,tree_order_statistics_node_update>;
const int N=4e5+100;
const int M=5001;
const int B=447;
const int mod=998244353;
const ll INF=1e18;
const int dx[]={1,-1,0,0};
const int dy[]={0,0,1,-1};
const double eps=1e-6;
int n;
vector<int>f[2];
int d[N];
void upd(int r,int x){
for(;r<=2*n;r+=(-r&r)){
d[r]+=x;
}
}
int calc(int r){
int res=0;
for(;r>0;r-=(-r&r)){
res+=d[r];
}
return res;
}
void test(){
cin>>n;
for(int i=1;i<=n*2;i++){
char x;
cin>>x;
if(x=='W'){
f[0].push_back(i);
}
else{
f[1].push_back(i);
}
}
sort(f[0].begin(),f[0].end());
sort(f[1].begin(),f[1].end());
int ans=0;
for(int k=0;k<=n;k++){
vector<pair<int,int>>v;
for(int j=1;j<=2*n;j++){
d[j]=0;
}
for(int i=0;i<n;i++){
v.push_back({f[0][i],f[1][(i+k)%n]});
if(v.back().first>v.back().second){
swap(v.back().first,v.back().second);
}
}
sort(v.begin(),v.end());
int res=0;
for(auto [a,b]:v){
res+=(calc(b)-calc(a));
upd(b,1);
}
ans=max(ans,res);
}
cout<<ans<<'\n';
}
/*
*/
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
// cout.tie(nullptr);
int t2=1;
// cin>>t2;
for(int i=1;i<=t2;i++){
test();
}
}
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