import java.util.*;
import java.io.*;
public class election {
public static void main(String[] args) throws IOException{
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
PrintWriter pw = new PrintWriter(System.out);
StringTokenizer t = new StringTokenizer(br.readLine());
int n = Integer.parseInt(t.nextToken());
String votes = "";
votes = br.readLine();
segTree = new Segment[4 * n];
build(0, 0, n-1, votes);
t = new StringTokenizer(br.readLine());
int q = Integer.parseInt(t.nextToken());
for(int i = 0; i < q; i++) {
t = new StringTokenizer(br.readLine());
int curr1 = Integer.parseInt(t.nextToken()) - 1;
int curr2 = Integer.parseInt(t.nextToken()) - 1;
pw.println(query(0, curr1, curr2, 0, n-1, segTree).answer);
}
pw.close();
}
public static Segment[] segTree;
public static Segment query(int node, int start, int end, int j, int k, Segment[] segTree) {
if (k < j)return new Segment(0, 0, 0, 0);
if (k < start || j > end) {
return new Segment(0, 0, 0, 0);
}
if (start <= j && k <= end) {
return segTree[node];
}
int midPt = (j + k)/2;
return merge(query(node * 2 + 1, start, end, j, midPt, segTree), query(node * 2 + 2, start, end, midPt + 1, k, segTree));
}
public static void build(int node, int l, int r, String s) {
if (l == r) {
if (s.charAt(l) == 'T') segTree[node] = new Segment(1, 1, 1, 1);
else segTree[node] = new Segment(0, 0, -1, 0);
} else {
int mid = (l + r) / 2;
build(node * 2+1, l, mid, s);
build(node * 2 + 2, mid + 1, r, s);
segTree[node] = merge(segTree[node * 2+1], segTree[node * 2 + 2]);
}
}
public static Segment merge(Segment seg1, Segment seg2) {
int newL = Math.max(seg1.maxL, seg1.total + seg2.maxL);
int newR = Math.max(seg2.maxR, seg2.total + seg1.maxR);
int total = seg1.total + seg2.total;
int newAns = Math.max(Math.max(seg1.answer + seg2.total, seg1.total + seg2.answer), seg1.maxL + seg2.maxR);
return new Segment(newL, newR, total, newAns);
}
}
class Segment{
int maxL;
int maxR;
int total;
int answer;
public Segment(int a, int b, int c, int d) {
maxL = a;
maxR = b;
total = c;
answer = d;
}
public String toString() {
return maxL + " " + maxR + " " + total + " " + answer;
}
}
