//#include<bits/stdc++.h>
#include <cstdio>
#include <iostream>
using namespace std;
#pragma GCC optimize ("O3,unroll-loops")
#pragma GCC target ("tune=native,avx2")
//#pragma GCC optimize ("Ofast,unroll-loops,trapv")
//#pragma GCC target ("tune=native")
/*
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, int> pli;
typedef pair<int, ll> pil;
typedef pair<ll, ll> pll;
#define f first
#define s second
#define mkpr make_pair
#define pque priority_queue
#define pb push_back
#define pf push_front
#define vec vector
#define pf push_front
#define Yes cout << "Yes\n";
#define YES cout << "YES\n";
#define No cout << "No\n";
#define NO cout << "NO\n";
#define em(x) (bool)(x).empty()
#define all(x) (x).begin(), (x).end()
#define tc int tc;cin >> tc; while(tc--)
#define cps CLOCKS_PER_SEC
//setprecision
//int, vector<int>, greater<int>
*/
const int N = 5e5 + 5, P = 1e9 + 7;
int n, q;
char v[N];
int a[N], b[N];
int main() {
ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
cin >> n >> v >> q;
for (int i = 0; i < n; i++)
if (v[i] == 'T')
a[i] = 1;
else
a[i] = -1;
int l, r, ans, x;
while(q--) {
cin >> l >> r;
ans = x = 0;
l--;
for (int i = l; i < r; i++) {
x+=a[i];
if (x > 0)
ans++, b[i] = 0, x--;
else
b[i] = a[i];
}
x = ans;
for (int i = r - 1; i >= l; i--) {
x+=b[i];
ans = max(ans, x);
}
cout << ans << '\n';
}
}
