#include <bits/stdc++.h>
#define fi first
#define se second
#define mp make_pair
#define TASK ""
#define bit(x) (1LL << (x))
#define getbit(x, i) (((x) >> (i)) & 1)
#define ALL(x) (x).begin(), (x).end()
using namespace std;
template <typename T1, typename T2> bool mini(T1 &a, T2 b) {
if (a > b) {a = b; return true;} return false;
}
template <typename T1, typename T2> bool maxi(T1 &a, T2 b) {
if (a < b) {a = b; return true;} return false;
}
mt19937_64 rd(chrono::steady_clock::now().time_since_epoch().count());
int rand(int l, int r) {
return l + rd() % (r - l + 1);
}
const int N = 5e5 + 5;
const int oo = 1e9;
const long long ooo = 1e18;
const int mod = 1e9 + 7; // 998244353;
const long double pi = acos(-1);
struct segtree {
struct node {
int sum, minr;
node(int _sum = 0, int _minr = 0) {
sum = _sum;
minr = _minr;
}
node operator + (const node &p) const {
node res;
res.sum = sum + p.sum;
res.minr = min(p.minr, minr + p.sum);
return res;
}
};
int n;
vector <node> st;
segtree(int _n = 0) {
n = _n;
st.assign(4 * n + 5, node());
}
void update(int id, int l, int r, int pos, int val) {
if (l > pos || r < pos)
return;
if (l == r) {
st[id] = node(val, val);
return;
}
int mid = (l + r) >> 1;
update(id << 1, l, mid, pos, val);
update(id << 1 | 1, mid + 1, r, pos, val);
st[id] = st[id << 1] + st[id << 1 | 1];
}
void update(int pos, int val) {
update(1, 1, n, pos, val);
}
node getval(int id, int l, int r, int u, int v) {
if (l > v || r < u)
return node();
if (l >= u && r <= v)
return st[id];
int mid = (l + r) >> 1;
node lnode = getval(id << 1, l, mid, u, v);
node rnode = getval(id << 1 | 1, mid + 1, r, u, v);
return lnode + rnode;
}
int getval(int l, int r) {
return getval(1, 1, n, l, r).minr;
}
};
vector <int> qr[N];
int ans[N];
int bit[N];
int l[N];
int r[N];
int a[N];
int n, q;
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
#ifdef ONLINE_JUDGE
// freopen(TASK".inp","r",stdin);
// freopen(TASK".out","w",stdout);
#endif
cin >> n;
{
string s; cin >> s;
for (int i = 1; i <= n; i++)
a[i] = (s[i - 1] == 'C') ? 1 : -1;
}
cin >> q;
for (int i = 1; i <= q; i++) {
cin >> l[i] >> r[i];
qr[l[i]].push_back(i);
}
segtree st(n);
vector <int> pos;
for (int i = n; i >= 1; i--) {
if (a[i] < 0)
pos.push_back(-i);
else {
if (pos.size()) {
st.update(-pos.back(), -1);
pos.pop_back();
}
st.update(i, 1);
}
for (int ind : qr[i]) {
int cntdel = (int) pos.size() -
(lower_bound(ALL(pos), -r[ind]) - pos.begin());
ans[ind] = max(0, -st.getval(l[ind], r[ind])) + cntdel;
}
}
for (int i = 1; i <= q; i++)
cout << ans[i] << "\n";
return 0;
}
