#include<bits/stdc++.h>
using namespace std;
int n,t,x,y;
char s[500005];
struct node
{
int l,r,sum,ans;
} seg[2000005];
node merge(node lft,node rht)
{
node res;
res.sum=lft.sum+rht.sum;
res.l=max(lft.l,lft.sum+rht.l);
res.r=max(rht.r,rht.sum+lft.r);
res.ans=max({lft.l+rht.r,lft.ans+rht.sum,rht.ans+lft.sum});
return res;
}
void build(int tree,int st,int ed)
{
int md=(st+ed)/2;
if(st==ed)
{
if(s[st]=='T')
{
seg[tree].l=seg[tree].r=seg[tree].sum=seg[tree].ans=1;
}else
{
seg[tree].l=seg[tree].r=seg[tree].ans=0;
seg[tree].sum=-1;
}
return;
}
build(2*tree,st,md);
build(2*tree+1,md+1,ed);
seg[tree]=merge(seg[2*tree],seg[2*tree+1]);
}
node query(int tree,int st,int ed,int l,int r)
{
int md=(st+ed)/2;
if(st>r||ed<l)
{
return {0,0,0,0};
}
if(st>=l&&ed<=r)
{
return seg[tree];
}
return merge(query(2*tree,st,md,l,r),query(2*tree+1,md+1,ed,l,r));
}
int main()
{
ios_base::sync_with_stdio(0),cin.tie(0);
cin >> n >> s+1;
cin >> t;
build(1,1,n);
while(t--)
{
cin >> x >> y;
printf("%d\n",query(1,1,n,x,y).ans);
}
}
