#include <bits/stdc++.h>
using namespace std;
typedef pair<int, int> pi;
typedef vector<int> vi;
typedef vector<pi> vpi;
#define mp make_pair
#define f first
#define s second
#define sz(x) (int)(x).size()
#define all(x) begin(x), end(x)
#define pb push_back
#define bk back()
const int MOD = 1000000007;
struct SegTree{
const static int SZ = 524288;
int mn[2*SZ];
int lazy[2*SZ];
void init(){
for(int i = 1; i < 2*SZ; i++){
mn[i] = 0;
lazy[i] = 0;
}
}
void pull(int ind){
mn[ind] = min(mn[2*ind], mn[2*ind+1]);
}
void push(int ind){
mn[ind]+=lazy[ind];
if(ind < SZ){
lazy[2*ind]+=lazy[ind];
lazy[2*ind+1]+=lazy[ind];
}
lazy[ind] = 0;
}
void upd(int lo, int hi, int val, int ind = 1, int L = 0, int R = SZ-1){
push(ind);
if(R < lo || L > hi) return;
if(lo <= L && R <= hi){
lazy[ind]+=val;
push(ind);
//cout << ind << " " << L << " " << R << " " << mn[ind] << "\n";
return;
}
int M = (L+R)/2;
upd(lo, hi, val, 2*ind, L, M);
upd(lo, hi, val, 2*ind+1, M+1, R);
pull(ind);
}
int query(int lo, int hi, int ind = 1, int L = 0, int R = SZ-1){
push(ind);
if(R < lo || L > hi) return MOD;
if(lo <= L && R <= hi){
// cout << "L,R,mn: " << L << " " << R << " " << mn[ind] << " " << lazy[ind] << "\n";
// if(ind < SZ){
// cout << mn[2*ind] << " " << lazy[2*ind] << "\n";
// }
return mn[ind];
}
int M = (L+R)/2;
int Q1 = query(lo, hi, 2*ind, L, M);
int Q2 = query(lo, hi, 2*ind+1, M+1, R);
return min(Q1, Q2);
}
};
const int mx = 500005;
int bt[mx]; //keep track of removed stuff
void upd(int ind, int val){
assert(1 <= ind && ind < mx);
while(ind < mx){
bt[ind]+=val;
ind+=ind&-ind;
}
}
int sum(int ind){
assert(0 <= ind && ind < mx);
if(ind == 0) return 0;
int res = 0;
while(ind > 0){
res+=bt[ind];
ind-=ind&-ind;
}
return res;
}
int query(int l, int r){
return sum(r)-sum(l-1);
}
int N;
string votes;
int Q;
int L[mx];
int R[mx];
int ans[mx];
SegTree seg;
int pref[mx];
vi npos[2*mx]; //positions of x+1 --> x, shifted by mx. back is current
void INSERT(int ind){ //removing T at position ind
//cout << "INSERT " << ind << "\n";
upd(ind, 1);
seg.upd(1, ind, 1);
}
int QUERY(int l, int r){
//cout << "QUERY: " << l << " " << r << "\n";
int ans = query(l, r);
//cout << "origans: " << ans << "\n";
int ival = seg.query(r+1, r+1);
int mval = seg.query(l, r+1);
//if(l == 4 && r == 9){
// for(int i = 1; i <= 12; i++){
// cout << seg.query(i, i) << " ";
// }
// cout << "\n";
//cout << ival << " " << mval << "\n";
//}
return ans+ival-mval;
}
int main(){
cin >> N;
cin >> votes;
votes = "?" + votes;
cin >> Q;
for(int i = 1; i <= Q; i++){
cin >> L[i] >> R[i];
}
seg.init();
vpi queries;
for(int i = 1; i <= Q; i++){
queries.pb(mp(L[i], i));
}
sort(all(queries));
pref[1] = 0;
for(int i = 2; i <= N+1; i++){
pref[i] = pref[i-1];
if(votes[i-1] == 'C'){
pref[i]++;
}
else{
pref[i]--;
}
}
for(int i = N; i >= 1; i--){
if(votes[i] == 'T'){
//cout << "i, pref[i+1] " << i << " " << pref[i+1] << "\n";
npos[pref[i+1]+mx].pb(i);
}
}
for(int i = -1; i >= -N; i--){
if(sz(npos[i+mx])){
//cout << i << " " << npos[i+mx].bk << "\n";
INSERT(npos[i+mx].bk);
}
}
int cursum = 0;
for(int i = N+1; i >= 1; i--){
if(i != N+1){
if(votes[i] == 'C'){
cursum++;
}
else if(votes[i] == 'T'){
cursum--;
}
}
seg.upd(i, i, cursum);
}
int curL = 1;
for(int q = 0; q < Q; q++){
int qind = queries[q].s;
//cout << "qind: " << qind << "\n";
while(curL < L[qind]){
if(votes[curL] == 'C'){
if(sz(npos[pref[curL+1]-1+mx])){
INSERT(npos[pref[curL+1]-1+mx].bk);
}
}
else if(votes[curL] == 'T'){
npos[pref[curL+1]+mx].pop_back();
//ERASE(npos[pref[curL]+mx].bk); doesn't seem necessary?
}
curL++;
}
ans[qind] = QUERY(L[qind], R[qind]);
}
for(int i = 1; i <= Q; i++){
cout << ans[i] << "\n";
}
}
