#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
typedef tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update> pbds;
#define getar(ar,n) for(ll i=0;i<n;++i) cin>>ar[i]
#define show(n) cout<<n<<'\n'
#define all(v) v.begin(), v.end()
#define br cout<<"\n"
#define pb push_back
#define nl '\n'
#define yes cout<<"YES\n"
#define no cout<<"NO\n"
#define ret return
#define ll long long
#define ld long double
#define sza(x) ((int)x.size())
#define fi first
#define se second
const int mxN = 1e5 + 5;
const ll MOD = 1e9 + 7;
const ll INF = 1e9;
const ld EPS = 1e-9;
void lets_go() {
ll n,l,r,q;cin>>n;
string str;cin>>str;
cin>>q;
while(q--){
cin>>l>>r;--l,--r;
ll c=0,t=0,lft=0,rgt=0;
for(ll i=l;i<=r;++i){
if(str[i]=='T') ++t;
else ++c;
if(t>c)--t,++lft;
}
t=c=0;
for(ll i=r;i>=l;--i){
if(str[i]=='T') ++t;
else ++c;
if(t>c)--t,++rgt;
}
show(max(lft,rgt));
}
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
lets_go();
return 0;
}
