#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define pii pair<int,int>
#define ff first
#define ss second
#define pb push_back
#define vi vector<int>
#define fr(i,ii,iii) for(int i=ii;i<iii;i++)
const int N=2003;
int n,q;
string a,b;
void check(string&b){
int t=0,c=0;
for(auto&i:b){
t+=(i=='T');
c+=(i=='C');
if(t>c){
i='X';
t--;
}
}
}
int main(){
ios_base::sync_with_stdio(false);cin.tie(NULL);
cin>>n>>a>>q;
while(q--){
int l,r;cin>>l>>r;
b="";
fr(i,l-1,r)b+=a[i];
//cout<<b<<" ";
check(b);
reverse(b.begin(),b.end());
check(b);
int ans=0;
for(auto i:b)if(i=='X')ans++;
cout<<ans<<"\n";
}
}
