#include<bits/stdc++.h>
using namespace std;
void DBG() { cerr << "]\n"; }
template<class H, class... T> void DBG(H h, T... t) {
cerr << h; if(sizeof...(t)) cerr << ", ";
DBG(t...);
}
#ifdef LOCAL
#define dbg(...) cerr << "[" << #__VA_ARGS__ << "]: [", DBG(__VA_ARGS__)
#else
#define dbg(...) 0
#endif // LOCAL
#define FOR(i,a,b) for(int i = (a) ; i<(b) ; i++)
#define F0R(i,a) FOR(i,0,a)
#define ROF(i,a,b) for(int i = (b)-1 ; i>=(a) ; i--)
#define R0F(i,a) ROF(i,0,a)
#define each(e,a) for(auto &e : (a))
#define sz(v) (int)(v).size()
#define all(v) (v).begin(),(v).end()
#define rall(v) (v).rbegin(),(v).rend()
#define pb push_back
#define tcT template<class T
#define nl "\n"
using ll = long long;
using vi = vector<int>;
using pi = pair<int,int>;
using str = string;
tcT> using V = vector<T>;
tcT> using pqg = priority_queue<T,vector<T>,greater<T>>;
void setIO(string NAME = "") {
cin.tie(0)->sync_with_stdio(0);
if(sz(NAME)) {
freopen((NAME + ".inp").c_str(),"r",stdin);
freopen((NAME + ".out").c_str(),"w",stdout);
}
}
const int MX = 1<<19;
struct Nod {
int mncst, mxp, mxs, sum;
};
Nod comb(const Nod&lf, const Nod&rh) {
return {
max({lf.mxp + rh.mxs, lf.sum + rh.mncst, lf.mncst + rh.sum}),
max(lf.mxp, lf.sum + rh.mxp),
max(rh.mxs, rh.sum + lf.mxs),
lf.sum + rh.sum,
};
}
Nod st[MX<<1];
int N;
str s;
void build(int ind = 1, int L = 1, int R = N) {
if(L == R) {
if(s[L-1] == 'T') st[ind] = {1, 1, 1, 1};
else st[ind] = {0,0,0,-1};
}
else {
int mid = (L + R) >> 1;
build(ind<<1, L, mid);
build(ind<<1|1, mid+1, R);
st[ind] = comb(st[ind<<1], st[ind<<1|1]);
}
}
Nod query(int l, int r, int ind = 1, int L = 1, int R = N) {
if(l > R || r < L) return {0,0,0,0};
if(l <= L && R <= r) return st[ind];
int mid = (L + R) >> 1;
return comb(query(l,r,ind<<1, L, mid), query(l,r,ind<<1|1, mid+1, R));
}
void solve() {
cin>>N>>s;
build();
int Q;
cin>>Q;
while(Q--) {
int l, r;
cin>>l>>r;
cout << query(l,r).mncst << nl;
}
}
int main() {
setIO();
int t=1;
//cin>>t;
while(t-->0) {
solve();
}
return 0;
}
