#include<bits/stdc++.h>
using namespace std;
#define int long long
const int MAX_VAL=200*1000+5;
int nbVal;
vector<int> initType;
string valDeb;
int cumu[MAX_VAL];
int calc(vector<int> typeSom) {
int rep=0;
vector<int> listeBla,listeNoir;
for (int i=0;i<2*nbVal;i++) {
if (typeSom[i]==0) {
listeBla.push_back(i);
}
else {
listeNoir.push_back(i);
}
}
for (int j=0;j<nbVal;j++) {
cumu[j]=-nbVal;
}
int deb,fin,mid,premSup;
for (int i=0;i<nbVal;i++) {
deb=0;
fin=nbVal;
while (deb!=fin) {
mid=(deb+fin)/2;
if (listeNoir[mid]<listeBla[i]) {
deb=mid+1;
}
else {
fin=mid;
}
}
premSup=deb;
if (premSup>0) {
deb=0;
fin=premSup;
while (deb!=fin) {
mid=(deb+fin)/2;
if (listeBla[i]-listeNoir[mid]<nbVal) {
fin=mid;
}
else {
deb=mid+1;
}
}
for (int j=0;j<deb;j++) {
cumu[(j-i+nbVal)%nbVal]+=2*nbVal-listeBla[i];
}
for (int j=deb;j<premSup;j++) {
cumu[(j-i+nbVal)%nbVal]+=listeBla[i];
}
}
if (premSup<nbVal) {
deb=premSup;
fin=nbVal;
while (deb!=fin) {
mid=(deb+fin)/2;
if (listeNoir[mid]-listeBla[i]>=nbVal) {
fin=mid;
}
else {
deb=mid+1;
}
}
for (int j=premSup;j<deb;j++) {
cumu[(j-i+nbVal)%nbVal]-=listeBla[i];
}
for (int j=deb;j<nbVal;j++) {
cumu[(j-i+nbVal)%nbVal]+=listeBla[i];
}
}
}
for (int i=0;i<nbVal;i++) {
deb=0;
fin=nbVal;
while (deb!=fin) {
mid=(deb+fin)/2;
if (listeBla[mid]<listeNoir[i]) {
deb=mid+1;
}
else {
fin=mid;
}
}
premSup=deb;
if (premSup>0) {
deb=0;
fin=premSup;
while (deb!=fin) {
mid=(deb+fin)/2;
if (listeNoir[i]-listeBla[mid]<nbVal) {
fin=mid;
}
else {
deb=mid+1;
}
}
for (int j=0;j<deb;j++) {
cumu[(i-j+nbVal)%nbVal]+=2*nbVal-listeNoir[i];
}
for (int j=deb;j<premSup;j++) {
cumu[(i-j+nbVal)%nbVal]+=listeNoir[i];
}
}
if (premSup<nbVal) {
deb=premSup;
fin=nbVal;
while (deb!=fin) {
mid=(deb+fin)/2;
if (listeBla[mid]-listeNoir[i]>=nbVal) {
fin=mid;
}
else {
deb=mid+1;
}
}
for (int j=premSup;j<deb;j++) {
cumu[(i-j+nbVal)%nbVal]-=listeNoir[i];
}
for (int j=deb;j<nbVal;j++) {
cumu[(i-j+nbVal)%nbVal]+=listeNoir[i];
}
}
}
for (int j=0;j<nbVal;j++) {
rep=max(rep,cumu[j]/2);
}
return rep;
}
signed main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
cin>>nbVal;
cin>>valDeb;
for (int i=0;i<2*nbVal;i++) {
if (valDeb[i]=='W') {
initType.push_back(0);
}
else {
initType.push_back(1);
}
}
cout<<calc(initType)<<endl;
return 0;
}
