#include<bits/stdc++.h>
#include<ext/pb_ds/assoc_container.hpp>
using namespace std;
using namespace __gnu_pbds;
using i64 = long long;
template<class T>
using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
#define int i64
#define vi vector<int>
#define vvi vector<vi>
#define vb vector<bool>
#define pii pair<int, int>
#define fi first
#define se second
#define sz(x) (int)(x).size()
struct SegTree{
struct Node{
int sum, pref, suff, ans;
};
vector<Node> st;
SegTree(int n) : st(4 * n) {}
inline Node combine(const Node &a, const Node &b){
Node c;
c.sum = a.sum + b.sum;
c.pref = max(a.pref, a.sum + b.pref);
c.suff = max(b.suff, b.sum + a.suff);
c.ans = max({a.ans + b.sum, b.ans + a.sum, a.pref + b.suff});
return c;
}
inline void update(int pos, int val, int v, int tl, int tr){
if(tl == tr){
if(val == 1) st[v] = {1, 1, 1, 1};
else st[v] = {-1, 0, 0, 0};
return;
}
int mid = (tl + tr) / 2;
if(pos <= mid){
update(pos, val, 2 * v, tl, mid);
}
else{
update(pos, val, 2 * v + 1, mid + 1, tr);
}
st[v] = combine(st[2 * v], st[2 * v + 1]);
return;
}
inline Node query(int ql, int qr, int v, int tl, int tr){
if(ql > tr || qr < tl) return {0, 0, 0, 0};
if(ql <= tl && qr >= tr) return st[v];
int mid = (tl + tr) / 2;
return combine(query(ql, qr, 2 * v, tl, mid), query(ql, qr, 2 * v + 1, mid + 1, tr));
}
};
signed main(){
ios_base::sync_with_stdio(false); cin.tie(0);
int n, q, l, r;
string s;
cin >> n >> s >> q;
SegTree st(n);
for(int i = 0; i < n; i++){
st.update(i + 1, s[i] == 'T', 1, 1, n);
}
while(q--){
cin >> l >> r;
cout << st.query(l, r, 1, 1, n).ans << "\n";
}
return 0;
}
