#include <bits/stdc++.h>
#define long long ll
using namespace std;
const int MAX_N=1e6;
struct Node {
int sum, pref, suf, ans;
Node operator+(Node b) {
Node ret;
ret.sum = sum + b.sum;
ret.pref = max(pref, b.pref + sum);
ret.suf = max(b.suf, suf + b.sum);
ret.ans = max(max(ans + b.sum, b.ans + sum), pref + b.suf);
return ret;
}
};
string s;
Node seg[4*MAX_N];
int L,R;
void build(int node, int l, int r) {
if(l==r) {
if(s[l]=='T') seg[node].sum = seg[node].ans = seg[node].pref = seg[node].suf = 1;
else {
seg[node].sum = -1;
seg[node].pref = seg[node].suf = seg[node].ans = 0;
}
return;
}
int m = (l+r)/2;
build(2*node, l, m);
build(2*node+1, m+1, r);
seg[node] = seg[2*node] + seg[2*node+1];
}
Node check(int node, int l, int r) {
if(l>R or r<L) return {0, 0, 0, 0};
if(l>=L && r<=R) return seg[node];
else return check(2*node, l, (l+r)/2) + check(2*node+1, (l+r)/2+1, r);
}
void solve() {
int n;
cin >> n;
cin >> s;
int q;
cin >> q;
build(1, 0, n-1);
while(q--) {
int l,r;
cin >> l >> r;
--l, --r;
L=l, R=r;
cout << check(1, 0, n-1).ans << endl;
}
}
int main()
{
int T=1;
while(T--) solve();
return 0;
}
