ABC 105 was unrated, because of organizer's mistake. I hope that this contest is not unrated.

For the problem D I use a BIT to find the amount of numbers less than R and I sorted the queries to decrease the values of the BIT.

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> PII;
typedef pair<ll , ll> PLL;
typedef double ld;

#define pb push_back
#define all(c) c.begin(),c.end()
#define allr(c) c.rbegin(),c.rend()
#define MOD 1000000007
#define PI 3.14159265

#define MAX 501
vector<int> vec[MAX];

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    int n , m , q;
    cin >> n >> m >> q;
    int l , r;
    for (int i = 0; i < m; i++) {
        cin >> l >> r;
        vec[l].pb(r);
    }
    for (int i = 1; i <= n; i++) {
        sort(all(vec[i]));
    }

    int ans = 0;
    for (int i = 0; i < q; i++) {
        cin >> l >> r;
        ans = 0;
        for (int j = l; j <= r; j++) {
            int ind = lower_bound(all(vec[j]) , r + 1) - vec[j].begin();
            ans += (ind);
        }
        cout << ans << endl;
    }

    return 0;
}

The problem is that other types of contests don't happen often — last four contests were for "Beginners".

I expected at least problem D to be challenging but,compared to previous beginner contests,I felt that problem D was way too easier this time.