#include <bits/stdc++.h>
#define lid id * 2 + 1
#define rid id * 2 + 2
using namespace std;
struct node_t {
int mp, ms, tot, ans;
};
string votes;
vector<node_t> st;
void merge(node_t& l, node_t& r, node_t& cur) {
cur.mp = max(l.mp, r.mp + l.tot);
cur.ms = max(l.ms + r.tot, r.ms);
cur.tot = l.tot + r.tot;
cur.ans = max(max(l.tot + r.ans, l.ans + r.tot), l.mp + r.ms);
}
void build(int id, int l, int r) {
if (l == r) {
if (votes[l] == 'T') st[id] = {1, 1, 1, 1};
else st[id] = {0, 0, -1, 0};
return;
}
int mid = (l + r) / 2;
build(lid, l, mid);
build(rid, mid + 1, r);
merge(st[lid], st[rid], st[id]);
}
node_t quer(int id, int l, int r, int ql, int qr) {
if (l > qr or r < ql) return {0, 0, 0, 0};
if (ql <= l and r <= qr) return st[id];
int mid = (l + r) / 2;
node_t ret, L = quer(lid, l, mid, ql, qr), R = quer(rid, mid + 1, r, ql, qr);
merge(L, R, ret);
return ret;
}
int main() {
int n, q, i;
cin >> n >> votes >> q;
vector<pair<int, int>> ques(q);
for (i = 0; i < q; i++) cin >> ques[i].first >> ques[i].second;
st.resize(n * 4);
build(0, 0, n - 1);
for (auto& que : ques) {
que.first--;
que.second--;
cout << quer(0, 0, n - 1, que.first, que.second).ans << endl;
}
return 0;
}
