#include <bits/stdc++.h>
using namespace std;
#define MAXN 500010
long long n;
long long q;
string s;
pair<pair<long long,long long>,pair<long long,long long>> seg[MAXN*4];
void build(long long node,long long l,long long r)
{
if (l==r)
{
if (s[l-1]=='T') seg[node]={{1,1},{1,1}};
else seg[node]={{0,0},{-1,0}};
}
else
{
long long mid=(l+r)/2;
build(2*node,l,mid);
build(2*node+1,mid+1,r);
seg[node].first.first=max(seg[2*node].first.first,seg[2*node].second.first+seg[2*node+1].first.first);
seg[node].first.second=max(seg[2*node].first.second+seg[2*node+1].second.first,seg[2*node+1].first.second);
seg[node].second.first=seg[2*node].second.first+seg[2*node+1].second.first;
seg[node].second.second=max(max(seg[2*node].second.second+seg[2*node+1].second.first,seg[2*node].second.first+seg[2*node+1].second.second),seg[2*node].first.first+seg[2*node+1].first.second);
}
}
pair<pair<long long,long long>,pair<long long,long long>> sol(long long node,long long l,long long r,long long a,long long b)
{
if (a>b) return {{0,0},{0,0}};
if (l==a and r==b) return seg[node];
long long mid=(l+r)/2;
pair<pair<long long,long long>,pair<long long,long long>> val1=sol(2*node,l,mid,a,min(b,mid));
pair<pair<long long,long long>,pair<long long,long long>> val2=sol(2*node+1,mid+1,r,max(a,mid+1),b);
pair<pair<long long,long long>,pair<long long,long long>> val;
val.first.first=max(val1.first.first,val1.second.first+val2.first.first);
val.first.second=max(val1.first.second+val2.second.first,val2.first.second);
val.second.first=val1.second.first+val2.second.first;
val.second.second=max(max(val1.second.second+val2.second.first,val1.second.first+val2.second.second),val1.first.first+val2.first.second);
return val;
}
int main()
{
cin>>n>>s;
build(1,1,n);
cin>>q;
for (long long i=1;i<=q;i++)
{
long long l,r;
cin>>l>>r;
cout<<sol(1,1,n,l,r).second.second<<endl;
}
}
