WA SPOJ problem BGSHOOT

I am kinda stucked at this problem BGSHOOT . The jist of my logic is that I am compressing starting and ending time of all the animals and applying max segment tree on the newly constructed array consisting of all compressed co-ordinates(i.e. calculating maximum frequency in given range.)
Since you cannot see my solution on spoj and I am not able to attach cpp file, I am copy pasting my code below.

#include <bits/stdc++.h>
#define ll long long
#define ld long double
#define mod 1000000007
using namespace std;
#define pb push_back
#define mp make_pair
#define ff first
#define ss second
#define all(arr) arr.begin() , arr.end()
#define FAST ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL)
#define rep(i , a , n) for(int i = a ; i < n ; i++)
#define ms(arr , val) memset(arr , 0 , sizeof(arr))
#define siz(temp) temp.size()
#define len(temp) temp.length()
#define timepass 1073741824
#define int ll
#define MAXN 100005

vector<pair<int , int> > a(MAXN);
vector<int> seg(4*MAXN);
map<int , int> comp;
void build(int ind , int l , int r)
{
 if (l > r)
         return;
     if (l == r)
     {
         seg[ind] = a[l].ss;
         return;
     }
     int mi = (l + r) >> 1;
     build(2*ind + 1 , l , mi);
     build(2*ind + 2 , mi + 1 , r);
     seg[ind] = max(seg[2*ind + 1] , seg[2*ind + 2]);
}

int query(int ind , int l , int r , int ql , int qr)
{
    if (l > qr || r < ql)
       return 0;
    else if (ql <= l && r <= qr)
        return seg[ind];
    int mi = (l + r) >> 1;
    int x = query(2*ind + 1 , l , mi , ql , qr);
    int y = query(2*ind + 2 , mi + 1 , r , ql , qr);
    return max(x , y);
}
signed main()
{
    //build();
    int n;
    cin >> n;
    vector<pair<int ,int> > arr(n);
    map<int , int> ma;
    rep(i , 0 , n)
    {
        cin >> arr[i].ff >> arr[i].ss;
        ma[arr[i].ff]++;
        ma[arr[i].ss + 1]--;
    }
    a.resize(0);
    for (auto it : ma)
    {
        a.pb(mp(it.ff , it.ss));
        comp[it.ff] = a.size() - 1;
    }
    for (int i = 1 ; i < a.size() ; i++)
    {
        a[i].ss = a[i].ss + a[i - 1].ss;
        //cout << a[i].ff << " " << a[i - 1].ff << endl;
    }
    build(0 , 0 , a.size() - 1);
    int q;
    cin >> q;
    while(q--)
    {
  int l,r;
        cin >> l >> r;
        map<int , int> :: iterator it;
        it = comp.lower_bound(l);
        //cout << it->ff << " " << it->ss << endl;
        if (it == comp.end())
        {
            cout << 0 << endl;
            continue;
            it--;
        }
        l = it->ss;
        if (comp.find(r) != comp.end())
        {
            r = comp[r];
            //cout << "HI\n";
        }
        else if (comp.find(r) == comp.end())
        {
            it = comp.upper_bound(r);
            
            if (r < (comp.begin() -> ff))
            {
                cout << 0 << endl;
                continue;
                it++;
            }
            else if (it == comp.end())
                it--;
            r = it->ss;
        }
        cout << query(0 , 0 , a.size() - 1 , l , r) << endl;
    }
    return 0;
}

@vijju123 please help

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