#include <bits/stdc++.h>
using namespace std;
void fast() {
ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
}
void ran() {
srand(chrono::steady_clock::now().time_since_epoch().count());
}
long long get_rand() {
long long a = rand();
long long b = rand();
return a * (RAND_MAX + 1ll) + b;
}
void usaco() {
freopen("problem.in", "r", stdin);
freopen("problem.out", "w", stdout);
}
template<typename T>
using min_pq = priority_queue<T, vector<T>, greater<T>>;
// #define endl '\n'
// #define double long double
// #define int long long
// const int MOD = 1000 * 1000 * 1000 + 7;
// const int MOD = 998244353;
const int MXN = 500005;
int a[MXN];
int n;
string s;
struct info {
int mxpf, mxsf, sm, ans;
} seg[MXN * 4];
info get(int x) {
info res;
if (x == 1) {
res.mxpf = res.mxsf = res.sm = res.ans = 1;
}
else if (x == -1) {
res.mxpf = res.mxsf = 0;
res.sm = -1;
res.ans = 0;
}
return res;
}
info comb(info a, info b) {
info res;
res.mxpf = max(a.mxpf, a.sm + b.mxpf);
res.mxsf = max(b.mxsf, b.sm + a.mxsf);
res.sm = a.sm + b.sm;
res.ans = max(max(a.ans + b.sm, a.sm + b.ans), a.mxpf + b.mxsf);
return res;
}
void build(int ind, int l, int r) {
if (l == r) {
seg[ind] = get(a[l]);
return;
}
int m = (l + r) / 2;
build(ind*2, l, m);
build(ind*2+1, m+1, r);
seg[ind] = comb(seg[ind*2], seg[ind*2+1]);
}
vector<info> sto;
void solve(int ind, int l, int r, int ql, int qr) {
if (ql <= l && r <= qr) {
sto.push_back(seg[ind]);
return;
}
if (ql > r || qr < l) return;
int m = (l + r) / 2;
solve(ind*2, l, m, ql, qr);
solve(ind*2+1, m+1, r, ql, qr);
}
signed main() {
ran(); fast();
cin >> n;
cin >> s;
for (int i=0; i<n; i++) {
if (s[i] == 'T') a[i] = 1;
else a[i] = -1;
}
build(1, 0, n-1);
int w;
cin >> w;
while (w--) {
int l, r;
cin >> l >> r;
l--; r--;
sto.clear();
solve(1, 0, n-1, l, r);
info cr = sto[0];
for (int i=1; i<sto.size(); i++) cr = comb(cr, sto[i]);
cout << cr.ans << endl;
}
}
