#include<bits/stdc++.h>
using namespace std;
int n,q,lg[500005];
pair<int,int>pref[2][21][500005];
pair<int,int> findmax(int l,int r,int tp){
if(r<l) return {1e9,0};
int pw=lg[r-l+1];
pair<int,int>ans=min(pref[tp][pw][l],pref[tp][pw][r-(1<<pw)+1]);
// if(ans.first>0) return {0,0};
return ans;
}
int main(){
cin>>n;
string s;
cin>>s;
for(int i=2;i<=500000;i++) lg[i]=lg[i/2]+1;
for(int i=1;i<=n;i++){
pref[0][0][i].first=pref[0][0][i-1].first;
if(s[i-1]=='T') pref[0][0][i].first--;
else pref[0][0][i].first++;
pref[0][0][i].second=i;
}
for(int i=n;i>=1;i--){
pref[1][0][i].first=pref[1][0][i+1].first;
if(s[i-1]=='T') pref[1][0][i].first--;
else pref[1][0][i].first++;
pref[1][0][i].second=-i;
}
for(int pw=1;pw<=19;pw++){
for(int i=1;i<=n;i++){
for(int nm:{0,1}){
pref[nm][pw][i]=min(pref[nm][pw-1][i],pref[nm][pw-1][min(n,i+(1<<(pw-1)))]);
}
}
}
cin>>q;
for(int i=1;i<=q;i++){
int l,r;
cin>>l>>r;
pair<int,int> ind0=findmax(l,r,0),sh0=findmax(ind0.second+1,r,1);
pair<int,int> ind1=findmax(l,r,1),sh1=findmax(l,-ind1.second-1,0);
ind1.second*=-1;
sh0.second*=-1;
ind0.first-=pref[0][0][l-1].first;
sh1.first-=pref[0][0][l-1].first;
ind1.first-=pref[1][0][r+1].first;
sh0.first-=pref[1][0][r+1].first;
ind0.first=min(ind0.first,0);
ind1.first=min(ind1.first,0);
sh0.first=min(sh0.first,0);
sh1.first=min(sh1.first,0);
// cout<<"{"<<ind0.first<<","<<ind0.second<<"}"<<' ';
// cout<<"{"<<sh0.first<<","<<sh0.second<<"}"<<'|';
// cout<<"{"<<ind1.first<<","<<ind1.second<<"}"<<' ';
// cout<<"{"<<sh1.first<<","<<sh1.second<<"}"<<endl;
// cout<<l<<'-'<<r<<' ';
cout<<-min(ind0.first+sh0.first,ind1.first+sh1.first)<<endl;
}
}
