// Andrei-Costin Constantinescu
// O(NlogN)
#include <bits/stdc++.h>
using namespace std;
const int NMAX = 500000 + 5;
int N, v[NMAX];
struct Node {
int l, r;
int sum, minSuf;
Node(int _l = 0, int _r = 0, int _sum = 0, int _minSuf = 0):
l(_l), r(_r), sum(_sum), minSuf(_minSuf) {}
static Node singleNode(const int l, const int r, const int val) {
return Node(l, r, val, min(val, 0));
}
friend Node operator+(const Node &arg0, const Node &arg1) {
return Node(arg0.l, arg1.r, arg0.sum + arg1.sum, min(arg0.minSuf + arg1.sum, arg1.minSuf));
}
} tree[4 * NMAX];
void build(int node, int l, int r) {
if (l == r) {
tree[node] = Node :: singleNode(l, l, 1);
return ;
}
const int mid = (l + r) / 2;
build(2 * node, l, mid);
build(2 * node + 1, mid + 1, r);
tree[node] = tree[2 * node] + tree[2 * node + 1];
}
Node query(int node, int r) {
if (tree[node].r == r)
return tree[node];
const int mid = (tree[node].l + tree[node].r) / 2;
if (r <= mid)
return query(2 * node, r);
else
return query(2 * node, mid) + query(2 * node + 1, r);
}
void update(int node, int where, int val) {
if (tree[node].l == tree[node].r) {
v[where] = val;
tree[node] = Node :: singleNode(where, where, v[where]);
return ;
}
const int mid = (tree[node].l + tree[node].r) / 2;
if (where <= mid)
update(2 * node, where, val);
else
update(2 * node + 1, where, val);
tree[node] = tree[2 * node] + tree[2 * node + 1];
}
struct Query {
int r, pos;
Query(int _r = 0, int _pos = 0):
r(_r), pos(_pos) {}
};
vector <Query> queries[NMAX];
int answers[NMAX];
int main() {
cin >> N;
assert(1 <= N && N <= 500000);
string votes;
cin >> votes;
assert(static_cast <int>(votes.size()) == N);
for (int i = 1; i <= N; ++ i) {
assert(votes[i - 1] == 'C' || votes[i - 1] == 'T');
v[i] = votes[i - 1] == 'C' ? 1 : -1;
}
build(1, 1, N);
int Q = 0;
cin >> Q;
assert(1 <= Q && Q <= 500000);
for (int i = 1; i <= Q; ++ i) {
int l, r;
cin >> l >> r;
assert(1 <= l && l <= r && r <= N);
queries[l].emplace_back(r, i);
}
vector <int> stk;
for (int i = N; i; -- i) {
if (v[i] == -1)
stk.push_back(i), update(1, i, 0);
else {
if (!stk.empty())
update(1, stk.back(), v[stk.back()] - 1), stk.pop_back();
}
for (auto qr: queries[i]) {
const int l = i, r = qr.r;
answers[qr.pos] = upper_bound(stk.rbegin(), stk.rend(), r) - stk.rbegin() - query(1, r).minSuf;
}
}
for (int i = 1; i <= Q; ++ i)
cout << answers[i] << '\n';
return 0;
}
