#include <bits/stdc++.h>
//~ #include <ext/pb_ds/assoc_container.hpp> // Общий файл.
//~ #include <ext/pb_ds/tree_policy.hpp> // Содержит класс tree_order_statistics_node_update
using namespace std;
//~ using namespace __gnu_pbds;
typedef long long ll;
typedef pair <int, int> pii;
typedef pair <ll, ll> pll;
//~ typedef tree<int,null_type,less_equal<int>,rb_tree_tag,tree_order_statistics_node_update> ordered_set;
#define long unsigned long
#define pb push_back
#define mp make_pair
#define all(v) (v).begin(),(v).end()
#define rall(v) (v).rbegin(),(v).rend()
#define lb lower_bound
#define ub upper_bound
#define sz(v) int((v).size())
#define do_not_disturb ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define endl '\n'
#define PI 2*acos(0.0)
const int N = 5e5+7;
pii tree[N * 4];
int weight[N];
pii combine(pii a, pii b) {
return mp(a.first + b.first, max(b.second, a.second + b.first));
}
void update(int v, int l, int r, int pos, int val) {
if (l == r) {
tree[v].first = val;
tree[v].second = max(0, val);
return;
}
int mid = (l + r) >> 1;
if (pos <= mid) update(v * 2, l, mid, pos, val);
else update(v * 2 + 1, mid + 1, r, pos, val);
tree[v] = combine(tree[v * 2], tree[v * 2 + 1]);
}
pii get(int v, int l, int r, int ql, int qr) {
if (ql > r || l > qr) return mp(0, 0);
if (ql <= l && r <= qr) return tree[v];
int mid = (l + r) >> 1;
return combine(get(v * 2, l, mid, ql, qr), get(v * 2 + 1, mid + 1, r, ql, qr));
}
void solve(int test) {
int q, n;
string s;
cin >> n >> s >> q;
vector <int> queries[n], ans(q);
vector <int> l(q), r(q);
for (int i = 0; i < q; i++) {
cin >> l[i] >> r[i];
r[i]--; l[i]--;
queries[l[i]].pb(i);
}
deque <int> deleted;
for (int i = n - 1; i >= 0; i--) {
if (s[i] == 'T') {
deleted.push_front(i);
}
else {
if (sz(deleted)) {
update(1, 0, n - 1, deleted.front(), 1);
deleted.pop_front();
}
update(1, 0, n - 1, i, -1);
}
for (auto j : queries[i]) {
auto del = ub(all(deleted), r[j]) - deleted.begin();
auto res = get(1, 0, n - 1, i, r[j]);
ans[j] = res.second + del;
}
}
for (auto to : ans) cout << to << endl;
}
int main() {
do_not_disturb
int t = 1;
//~ cin >> t;
for (int i = 1; i <= t; i++) {
solve(i);
}
return 0;
}
