/*
ID: blackha5
TASK: test
LANG: C++
*/
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#define ff first
#define ss second
#define Maxn 500003
#define ll long long
#define pb push_back
#define Inf 1000000009
#define ppb() pop_back()
#define pii pair <int , int>
#define mid(x, y) (x + y) / 2
#define all(x) x.begin(),x.end()
#define llInf 1000000000000000009
#define tr(i, c) for(__typeof(c).begin() i = (c).begin() ; i != (c).end() ; i++)
using namespace std;
using namespace __gnu_pbds;
typedef tree <int, null_type, less <int>, rb_tree_tag, tree_order_statistics_node_update> order;
int n, q;
char a[Maxn];
int ans[Maxn];
int T[Maxn * 4][2];
vector <int> v, B;
vector <pii> A[Maxn];
void upd (int x, int y, int l, int r, int v) {
if (l == r) {
T[v][0] = y;
T[v][1] = min (y, 0);
return;
}
if (x <= mid (l, r))
upd (x, y, l, mid (l, r), v * 2);
else
upd (x, y, mid (l, r) + 1, r, v * 2 + 1);
T[v][0] = T[v * 2][0] + T[v * 2 + 1][0];
T[v][1] = min (0, min (T[v * 2 + 1][1], T[v * 2][1] + T[v * 2 + 1][0]));
}
void get (int x, int y, int l, int r, int v) {
if (l >= x and r <= y) {
B.pb (v);
return;
}
if (l > y or r < x)
return;
get (x, y, l, mid (l, r), v * 2);
get (x, y, mid (l, r) + 1, r, v * 2 + 1);
}
int main () {
//freopen ("file.in", "r", stdin);
//freopen ("file.out", "w", stdout);
//srand ((unsigned) time ( NULL ));
//int randomNumber = rand() % 10 + 1;
scanf ("%d %s %d", &n, &a, &q);
int cnt = 0;
while (cnt != q) {
int l, r;
scanf ("%d%d", &l, &r);
A[l].pb ({r, ++cnt});
}
for (int i = n; i >= 1; i--) {
if (a[i - 1] == 'C') {
upd (i, 1, 1, n, 1);
if (v.size() > 0) {
upd (v.back(), -1, 1, n, 1);
v.ppb();
}
}
else
v.pb (i);
for (auto j: A[i]) {
B.clear();
get (i, j.ff, 1, n, 1);
int x = 0, y = 0;
for (int k = B.size() - 1; k >= 0; k--)
x = min (x, y + T[B[k]][1]), y += T[B[k]][0];
int l = 1;
int r = v.size();
int pos = 0;
while (l <= r) {
int md = mid (l, r);
if (v[v.size() - md] <= j.ff)
pos = md, l = md + 1;
else
r = md - 1;
}
ans[j.ss] = max (-x, 0) + pos;
}
}
for (int i = 1; i <= q; i++)
printf ("%d\n", ans[i]);
return 0;
}
