#include<bits/stdc++.h>
using namespace std;
const int N = 5e5 + 5;
int n , a[N];
string s;
struct Node{
int L , R , cnt , ans;
Node operator+(Node y){
Node ret;
ret.cnt = cnt + y.cnt;
ret.L = max(L , cnt + y.L);
ret.R = max(y.R , y.cnt + R);
ret.ans = max({L + y.R , cnt + y.ans , ans + y.cnt});
return ret;
}
}T[4*N];
void B(int l = 0 , int r= n - 1 , int pos= 0){
if(l == r){
if(a[l] == 1) T[pos] = {1 , 1 , 1 , 1};
else T[pos] = {0 , 0 , -1 , 0};
return;
}
int mid = (l + r) >> 1;
B(l , mid , pos * 2 + 1);
B(mid + 1 , r , pos * 2 + 2);
T[pos] = T[pos * 2 + 1] + T[pos * 2 + 2];
}
Node get(int L , int R , int l =0 , int r= n - 1 ,int pos = 0){
if(r <L || R < l) return {0 , 0 ,0 , 0};
if(L <= l && r <= R) return T[pos];
int mid = (l + r) >> 1;
return get(L , R , l , mid , pos * 2 + 1) + get(L , R , mid + 1 , r ,pos * 2 + 2);
}
int main (){
ios_base::sync_with_stdio(0); cin.tie(0);
cin >> n >> s;
for(int i = 0; i < n; ++i){
if(s[i] == 'T') a[i] = 1;
else a[i] = -1;
}
B();
int q;
cin >> q;
while(q--){
int a, b;
cin >> a >> b;--a; --b;
cout << get(a , b).ans << endl;
}
return 0;
}
