#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;
const int MAXN = 5e5 + 10;
char c[MAXN];
struct Segment {
struct Node {
int pf, sf, sum, ans;
Node()
{
pf = sf = sum = ans = 0;
}
} node[MAXN << 2];
Node merge(Node l, Node r)
{
Node res;
res.pf = max(l.pf, l.sum + r.pf);
res.sf = max(r.sf, r.sum + l.sf);
res.sum = l.sum + r.sum;
res.ans = max(max(l.ans + r.sum, r.ans + l.sum), l.pf + r.sf);
return res;
}
void initialize(int id, int l, int r)
{
if (l + 1 == r)
{
if (c[l] == 'T')
node[id].pf = node[id].sf = node[id].sum = node[id].ans = 1;
else
{
node[id].pf = node[id].sf = node[id].ans = 0;
node[id].sum = -1;
}
return;
}
int mid = (l + r) >> 1;
initialize(id << 1 | 0, l, mid);
initialize(id << 1 | 1, mid, r);
node[id] = merge(node[id << 1 | 0], node[id << 1 | 1]);
}
Node get(int id, int L, int R, int l, int r)
{
if (L == l && R == r)
{
return node[id];
}
int mid = (L + R) >> 1;
Node res;
if (l < mid)
res = merge(res, get(id << 1 | 0, L, mid, l, min(r, mid)));
if (r > mid)
res = merge(res, get(id << 1 | 1, mid, R, max(l, mid), r));
return res;
}
} Seg;
int main()
{
int n, q;
cin >> n;
for (int i = 1; i <= n; i++)
cin >> c[i];
Seg.initialize(1, 1, n + 1);
cin >> q;
while (q--)
{
int l, r;
cin >> l >> r;
auto ans = Seg.get(1, 1, n + 1, l, r + 1);
cout << ans.ans << endl;
}
return 0;
}
