# include <bits/stdc++.h>
using namespace std;
#define f first
#define s second
// #define int long long
#define pii pair <int, int>
#define pb push_back
const int N = 5e5 + 5;
int t,n,a[N],sf[N],pr[N],ans[N];
int tree[4 * N], lazy[4 * N];
vector <pii> v[N];
stack <int> st;
string s;
int merge(int a, int b) {
return min(a, b);
}
void build(int node, int le, int ri) {
if (le == ri) {
tree[node] = sf[le];
// lazy[node] = 0;
return ;
}
int mid = (le + ri) / 2;
build(2 * node, le, mid);
build(2 * node + 1, mid + 1, ri);
tree[node] = merge(tree[2 * node], tree[2 * node + 1]);
}
void push(int node, int le, int ri) {
if (!lazy[node]) return ;
tree[node] += lazy[node];
if (le != ri) {
lazy[2 * node] += lazy[node];
lazy[2 * node + 1] += lazy[node];
}
lazy[node] = 0;
}
void update(int node, int le, int ri, int start, int end, int val) {
push(node,le,ri);
if (le > end || ri < start) return ;
if (le >= start && ri <= end) {
lazy[node] = val;
push(node,le,ri);
return ;
}
int mid = (le + ri) / 2;
update(2 * node,le,mid,start,end,val);
update(2 * node + 1, mid + 1, ri, start, end,val);
tree[node] = merge(tree[2 * node], tree[2 * node + 1]);
}
int getans(int node, int le, int ri, int start, int end) {
push(node,le,ri);
if (le > end || ri < start) return 1e9;
if (le >= start && ri <= end) {
return tree[node];
}
int mid = (le + ri) / 2;
return merge(getans(2 * node, le, mid,start,end), getans(2 * node + 1, mid + 1, ri, start, end));
}
int tree_f[N];
void upd(int idx, int val) {
// cout<<"upd "<<idx<<" "<<val<<"\n";
for (int i = idx; i < N; i+=i&(-i)) {
tree_f[i] += val;
}
}
int get(int idx) {
int pas = 0;
for (int i = idx; i > 0; i-=i&(-i)) {
pas += tree_f[i];
}
return pas;
}
main() {
std::ios_base::sync_with_stdio(false),cin.tie(0),cout.tie(0);
cin>>n>>s; s = "@" + s;
for (int i = 1; i <= n; i++) {
pr[i] = pr[i - 1] + (s[i] == 'C' ? 1 : -1);
}
for (int i = n; i >= 1; i--) {
sf[i] = sf[i + 1] + (s[i] == 'C' ? 1 : -1);
}
build(1, 1, n);
int q; cin>>q;
for (int i = 1; i <= q; i++) {
int l, r; cin>>l>>r;
v[l].pb({r, i});
}
for (int i = n; i >= 1; i--) {
if (s[i] == 'T') {
st.push(i); update(1, 1, n, 1, i, 1); upd(i, 1);
} else {
if (!st.empty()) {
int x = st.top(); st.pop();
update(1, 1, n, 1, x, -1); upd(x, -1);
}
}
for (pii sth : v[i]) {
int ri = sth.f; int id = sth.s;
ans[id] = get(ri) + max(0, -(getans(1,1, n, i, ri) - sf[ri + 1] - get(n) + get(ri)));
}
}
for (int i = 1; i <= q; i++) {
cout<<ans[i]<<"\n";
}
}
