#include <bits/stdc++.h>
using i64 = long long;
using namespace std;
constexpr int inf = 1E9;
struct Info {
int x;
Info(int x = -inf) : x(x) {}
};
Info operator+(const Info &a, const Info &b) {
return Info(max(a.x, b.x));
}
struct Tag {
int x;
Tag(int x = 0) : x(x) {}
};
void apply(Tag &a, const Tag &b) {
a.x += b.x;
}
void apply(Info &a, const Tag &b) {
a.x += b.x;
}
template<class Info, class Tag,
class Merge = std::plus<Info>>
struct LazySegmentTree {
const int n;
const Merge merge;
std::vector<Info> info;
std::vector<Tag> tag;
LazySegmentTree(int n) : n(n), merge(Merge()), info(4 << std::__lg(n)), tag(4 << std::__lg(n)) {}
LazySegmentTree(std::vector<Info> init) : LazySegmentTree(init.size()) {
std::function<void(int, int, int)> build = [&](int p, int l, int r) {
if (r - l == 1) {
info[p] = init[l];
return;
}
int m = (l + r) / 2;
build(2 * p, l, m);
build(2 * p + 1, m, r);
pull(p);
};
build(1, 0, n);
}
void pull(int p) {
info[p] = merge(info[2 * p], info[2 * p + 1]);
}
void apply(int p, const Tag &v) {
::apply(info[p], v);
::apply(tag[p], v);
}
void push(int p) {
apply(2 * p, tag[p]);
apply(2 * p + 1, tag[p]);
tag[p] = Tag();
}
void modify(int p, int l, int r, int x, Info v) {
if (r - l == 1) {
info[p] = v;
return;
}
int m = (l + r) / 2;
push(p);
if (x < m) {
modify(2 * p, l, m, x, v);
} else {
modify(2 * p + 1, m, r, x, v);
}
pull(p);
}
void modify(int x, Info v) {
modify(1, 0, n, x, v);
}
Info rangeQuery(int p, int l, int r, int x, int y) {
if (l >= y || r <= x) {
return Info();
}
if (l >= x && r <= y) {
return info[p];
}
int m = (l + r) / 2;
push(p);
return merge(rangeQuery(2 * p, l, m, x, y), rangeQuery(2 * p + 1, m, r, x, y));
}
Info rangeQuery(int l, int r) {
return rangeQuery(1, 0, n, l, r);
}
void rangeApply(int p, int l, int r, int x, int y, const Tag &v) {
if (l >= y || r <= x) {
return;
}
if (l >= x && r <= y) {
apply(p, v);
return;
}
int m = (l + r) / 2;
push(p);
rangeApply(2 * p, l, m, x, y, v);
rangeApply(2 * p + 1, m, r, x, y, v);
pull(p);
}
void rangeApply(int l, int r, const Tag &v) {
return rangeApply(1, 0, n, l, r, v);
}
};
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int n;
cin >> n;
string S;
cin >> S;
int q;
cin >> q;
vector<vector<pair<int, int>>> Q(n);
vector<int> ans(q);
for (int i = 0; i < q; i++) {
int l, r;
cin >> l >> r;
l--;
r--;
Q[l].emplace_back(r, i);
}
stack<int> s;
LazySegmentTree<Info, Tag> res(n), f(n);
for (int i = 0; i < n; i++) {
res.modify(i, Info(0));
f.modify(i, Info(0));
}
for (int i = n - 1; i >= 0; i--) {
if (S[i] == 'T') {
res.rangeApply(i, n, 1);
s.push(i);
} else {
if (!s.empty()) {
res.rangeApply(s.top(), n, -1);
f.rangeApply(s.top(), n, -1);
s.pop();
}
f.rangeApply(i, n, 1);
}
for (auto [r, id] : Q[i]) {
ans[id] = res.rangeQuery(r, r + 1).x + (f.rangeQuery(i, r + 1).x - f.rangeQuery(r, r + 1).x);
}
}
for (int i = 0; i < q; i++) {
cout << ans[i] << "\n";
}
return 0;
}
