#include<bits/stdc++.h>
using namespace std;
const int maxn = 500100;
struct Node {
int L, R, tot, Ans;
Node operator + (Node B) {
Node ret;
ret.L = max(L, tot + B.L);
ret.R = max(B.R, R + B.tot);
ret.tot = tot + B.tot;
ret.Ans = max({Ans + B.tot, tot + B.Ans, L + B.R});
return ret;
}
};
Node T[(maxn << 2)];
string S;
int N;
void build(int v = 1, int l = 1, int r = N) {
if (l == r) {
if (S[l] == 'T') T[v] = {1, 1, 1, 1};
else T[v] = {0, 0, -1, 0};
return;
}
int md = (l + r) >> 1;
build(v << 1, l, md);
build(v << 1 | 1, md + 1, r);
T[v] = T[v << 1] + T[v << 1 | 1];
}
Node get(int v, int l, int r, int x, int y) {
if (l > y || x > r) return {0, 0, 0, 0};
if (x <= l && r <= y) return T[v];
int md = (l + r) >> 1;
return get(v << 1, l, md, x, y)
+ get(v << 1 | 1, md + 1, r, x, y);
}
int main() {
ios::sync_with_stdio(0); cin.tie(0);
// freopen("election.in", "r", stdin);
// freopen("election.out", "w", stdout);
cin >> N >> S;
S = ' ' + S;
build();
int Q; cin >> Q;
while (Q--) {
int L, R; cin >> L >> R;
cout << get(1, 1, N, L, R).Ans << '\n';
}
return 0;
}
