#include <bits/stdc++.h>
#define fi first
#define se second
#define mp make_pair
#define all(x) x.begin(), x.end()
using namespace std;
template <class X, class Y> bool minimize(X &a, Y b) {
if (a > b) return a = b, true;
return false;
}
template <class X, class Y> bool maximize(X &a, Y b) {
if (a < b) return a = b, true;
return false;
}
struct segment_tree {
struct Node {
int sum, ans;
Node(int _sum = 0, int _ans = 0) {
sum = _sum;
ans = _ans;
}
Node operator + (const Node &oth) const {
return Node(sum + oth.sum, min(oth.ans, ans + oth.sum));
}
};
vector<Node> t;
int n;
segment_tree(int _n) : n(_n) {
t.resize((n << 2) + 7);
}
void modify(int node, int l, int r, int p, int v) {
if (l > p || r < p) {
return;
}
if (l == r) {
t[node] = Node(v, v);
} else {
int mid = (l + r) >> 1;
modify(node << 1, l, mid, p, v);
modify(node << 1|1, mid + 1, r, p, v);
t[node] = t[node << 1] + t[node << 1|1];
}
}
Node get(int node, int l, int r, int u, int v) {
if (l > v || r < u) {
return Node(0, 0);
}
if (u <= l && r <= v) {
return t[node];
}
int mid = (l + r) >> 1;
Node L = get(node << 1, l, mid, u, v);
Node R = get(node << 1|1, mid + 1, r, u, v);
return L + R;
}
void modify(int p, int v) {
modify(1, 1, n, p, v);
}
int get(int l, int r) {
return -get(1, 1, n, l, r).ans;
}
};
const int N = 5e5 + 7;
int n;
int a[N];
int res[N];
string s;
vector<pair<int, int>> pos[N];
signed main() {
cin.tie(0)->sync_with_stdio(0);
cin >> n >> s;
for (int i = 1; i <= n; i ++) {
a[i] = (s[i - 1] == 'C' ? 1 : -1);
}
int q; cin >> q;
for (int i = 1; i <= q; i ++) {
int l, r; cin >> l >> r;
pos[l].emplace_back(r, i);
}
vector<int> s;
segment_tree st(n);
for (int l = n; l > 0; l --) {
if (a[l] == 1) {
if (!s.empty()) {
st.modify(-s.back(), -1);
s.pop_back();
}
st.modify(l, 1);
} else {
s.push_back(-l);
}
for (pair<int, int> x: pos[l]) {
int r, i; tie(r, i) = x;
int add = lower_bound(all(s), - r) - s.begin();
add = (int) s.size() - add;
res[i] = max(0, st.get(l, r)) + add;
}
}
for (int i = 1; i <= q; i ++) {
cout << res[i] << '\n';
}
return 0;
}
