#include <bits/stdc++.h>
using namespace std;
#define int long long
using vi = vector<int>;
using vvi = vector<vi>;
signed main() {
int n; cin >> n;
string s; cin >> s;
int t; cin >> t;
while (t--) {
int l, r; cin >> l >> r;
l--; r--;
int counter = 0, ans = 0;
vi null(n, 0);
for (int i = l; i <= r; i++) {
if (counter == 0 and s[i] == 'T') {
ans++;
null[i] = 1;
} else if (s[i] == 'T') counter--;
else counter++;
}
counter = 0;
for (int i = r; i >= l; i--) {
if (null[i]) continue;
if (counter == 0 and s[i] == 'T') {
ans++;
null[i] = 1;
} else if (s[i] == 'T') counter--;
else counter++;
}
cout << ans << "\n";
}
}
