#include<bits/stdc++.h>
using namespace std;
void solve(){
int n, q;
cin >> n;
string ST;
cin >> ST;
int p[n+2], s[n+2];
p[0] = s[n+1] = 0;
for(int i = 0;i < n;i++){
if(ST[i]=='T') p[i+1]=s[i+1]=1;
else p[i+1]=s[i+1]=-1;
p[i+1]+=p[i];
}
for(int i = n;i >= 0;i--) s[i]+=s[i+1];
cin >> q;
while(q--){
int l, r;cin >> l >> r;
int ans = 0;
int P[n+2], S[n+2];
P[l-1]=S[r+1]=0;
for(int i = l;i <= r;i++) P[i] = max(P[i-1], p[i]-p[l-1]);
for(int i = r;i >= l;i--) S[i] = max(S[i+1], s[i]-s[r+1]);
for(int i = l-1;i <= r;i++) ans = max(ans, P[i]+S[i+1]);
cout << ans << '\n';
}
}
int main(){
ios_base::sync_with_stdio(false);
cin.tie(0);
solve();
}
