#pragma GCC optimize ("Ofast")
#pragma GCC target ("avx,avx2,fma")
#include"bits/stdc++.h"
using namespace std;
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
template<class x>
using ordered_set = tree<x, null_type,less<x>, rb_tree_tag,tree_order_statistics_node_update>;
#define int long long
#define endl '\n'
#define mod 1000000007
//\
#define mod 1686876991
const int maxn = 500001;
const int N = exp2(ceil(log2(maxn)));
int Left, Right;
struct node {
int sum;
int mp, ms;
int ans;
};
node operator +(const node a, const node b) {
node c;
c.sum = a.sum + b.sum;
c.mp = max(a.mp, b.mp + a.sum);
c.ms = max(b.ms, a.ms + b.sum);
c.ans = max({a.mp + b.ms, b.ans + a.sum, a.ans + b.sum});
return c;
}
node seg[2 * N];
node Query (int l = 1, int r = N, int ind = 1) {
if (l > Right || r < Left) assert(0);
if (l >= Left and r <= Right) return seg[ind];
int m = (l + r) / 2;
if (Left > m) return Query(m + 1, r, ind * 2 + 1);
if (Right <= m) return Query(l, m, ind * 2);
return Query(l, m, ind * 2) + Query(m + 1, r, ind * 2 + 1);
}
signed main () {
cin.tie(0)->sync_with_stdio(0);
int n, q;
string s;
cin >> n >> s >> q;
for (int i = 0 ; i < n ; i++) {
if (s[i] == 'T') {
seg[N + i] = {1, 1, 1, 1};
} else {
seg[N + i] = {-1, 0, 0, 0};
}
}
for (int i = N - 1 ; i ; i--) seg[i] = seg[i * 2] + seg[i * 2 + 1];
while (q--) {
cin >> Left >> Right;
cout << Query().ans << endl;
}
}
