#include <bits/stdc++.h>
using namespace std;
const int maxn = 5e5 + 10;
int n;
string s;
bool visited[maxn];
int solve(int S, int E){
int balance = 0;
int ret = 0;
memset(visited, false, sizeof visited);
for(int i = S; i <= E; i ++){
if(s[i] == 'C'){
balance ++;
}
else{
balance --;
}
if(balance < 0){
balance = 0;
visited[i] = true;
ret ++;
}
}
balance = 0;
for(int i = E; i >= S; i --){
if(s[i] == 'C'){
balance ++;
}
else if(!visited[i] and s[i] == 'T'){
balance --;
}
if(balance < 0){
balance = 0;
ret ++;
}
}
return ret;
}
int main()
{
ios_base::sync_with_stdio(false);
cin >> n >> s;
int q;
cin >> q;
for(int i = 0; i < q; i ++){
int a, b;
cin >> a >> b;
a --;
b --;
cout << solve(a, b) << endl;
}
return 0;
}
