#pragma GCC optimize ("O3")
#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx,avx2,fma")
#include <bits/stdc++.h>
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>
// author: amin_2008
#define ios ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0)
#define ll long long
#define vi vector<int>
#define vs vector<string>
#define vc vector<char>
#define vl vector<ll>
#define all(v) v.begin(), v.end()
#define rall(v) v.rbegin(), v.rend()
#define pb push_back
#define bpc __builtin_popcount
#define pii pair<int, int>
#define pll pair<ll, ll>
#define piii pair<pii, int>
#define vpii vector<pii>
#define vpll vector<pll>
#define vvpii vector<vpii>
#define vvi vector<vector<int>>
#define vvl vector<vector<ll>>
#define ins insert
#define ts to_string
#define F first
#define S second
#define lb lower_bound
#define ub upper_bound
#define ld long double
#define ull unsigned long long
#define endl '\n'
//#define int ll
using namespace std;
using namespace __gnu_pbds;
using namespace __cxx11;
template<class T> using ordered_set = tree<T, null_type,less<T>, rb_tree_tag,tree_order_statistics_node_update>;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
const ll inf = 2e5 * 1e9;
const int mod = 1e9+7;
const int sz = 5e5+5;
const int N = 500001;
const int logg = 18;
const int P = 40000005;
const ll M = 8e5+5;
//int a[sz];
vi st[sz << 2]{vi(4)};
vi merge(vi a, vi b)
{
vi res(4);
res.front() = a.front() + b.front();
res[1] = max(a[1], b[1] + a.front());
res[2] = max(b[2], a[2] + b.front());
res[3] = max(max(max(a[3] + b.front(), b[3] + a.front()), 0), a[1] + b[2]);
return res;
}
string s;
void build(int l, int r, int in)
{
if ( l == r )
{
int a = ( s[l] == 'T' ), b = a;
if ( !b ) b--;
st[in] = {b, a, a, a};
return;
}
int mid = ( l + r ) >> 1;
build(l, mid, in << 1);
build(mid+1, r, in << 1 | 1);
st[in] = merge(st[in << 1], st[in << 1 | 1]);
}
vi get(int a, int b, int l, int r, int in)
{
if ( a > r or b < l ) return {0, 0, 0, 0};
if ( a <= l and r <= b ) return st[in];
int mid = ( l + r ) >> 1;
return merge(get(a, b, l, mid, in << 1), get(a, b, mid+1, r, in << 1 | 1));
}
void solve()
{
int n;
cin >> n >> s;
build(0, n - 1, 1);
int q;
cin >> q;
while ( q-- )
{
int l, r;
cin >> l >> r;
l--, r--;
cout << get(l, r, 0, n - 1, 1)[3] << endl;
}
}
signed main()
{
ios;
//precompute();
int t = 1;
//cin >> t;
while(t--){
solve();
}
}
