#include <bits/stdc++.h>
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
using namespace std;
int n, q;
string s;
struct node {
int L, R;
int sum;
int best;
node operator + (const node& other) const {
node ret;
ret.sum = sum + other.sum;
ret.L = max(L, sum + other.L);
ret.R = max(other.R, other.sum + R);
ret.best = max({L + other.R, best + other.sum, sum + other.best});
return ret;
}
} st[2000010];
void build(int id, int L, int R) {
if (L == R) {
if (s[L - 1] == 'T') st[id] = {1, 1, 1, 1};
else st[id] = {0, 0, -1, 0};
return;
}
int mid = L + R >> 1;
build(id * 2, L, mid);
build(id * 2 + 1, mid + 1, R);
st[id] = st[id * 2] + st[id * 2 + 1];
}
node get(int id, int L, int R, int u, int v) {
if (u <= L && R <= v) return st[id];
int mid = L + R >> 1;
if (v <= mid) return get(id * 2, L, mid, u, v);
if (u > mid) return get(id * 2 + 1, mid + 1, R, u, v);
return get(id * 2, L, mid, u, v) + get(id * 2 + 1, mid + 1, R, u, v);
}
int main() {
ios :: sync_with_stdio(0); cin.tie(0); cout.tie(0);
cin >> n;
cin >> s;
build(1, 1, n);
cin >> q;
while (q--) {
int l, r;
cin >> l >> r;
cout << get(1, 1, n, l, r).best << '\n';
}
}
