Problem:
Score: 400 points

Problem Statement

In Takahashi Kingdom, there is a east-west railroad and N cities along it, numbered 1, 2, 3, ..., N from west to east.
A company called AtCoder Express possesses M trains, and the train i runs from City L_i to City R_i (it is possible that L_i = R_i).
Takahashi the king is interested in the following Q matters:

The number of the trains that runs strictly within the section from City p_i to City q_i, that is, the number of trains j such that p_i \leq L_j and R_j \leq q_i.

Although he is genius, this is too much data to process by himself. Find the answer for each of these Q queries to help him.

Constraints

N is an integer between 1 and 500 (inclusive).

M is an integer between 1 and 200 \ 000 (inclusive).

Q is an integer between 1 and 100 \ 000 (inclusive).

1 \leq L_i \leq R_i \leq N (1 \leq i \leq M)

1 \leq p_i \leq q_i \leq N (1 \leq i \leq Q)

Input

Input is given from Standard Input in the following format:

N M Q
L_1 R_1
L_2 R_2
:
L_M R_M
p_1 q_1
p_2 q_2
:
p_Q q_Q

Output

Print Q lines. The i-th line should contain the number of the trains that runs strictly within the section from City p_i to City q_i.

Sample Input 1

2 3 1
1 1
1 2
2 2
1 2

Sample Output 1

3

As all the trains runs within the section from City 1 to City 2, the answer to the only query is 3.

Sample Input 2

10 3 2
1 5
2 8
7 10
1 7
3 10

Sample Output 2

1
1

The first query is on the section from City 1 to 7. There is only one train that runs strictly within that section: Train 1.
The second query is on the section from City 3 to 10. There is only one train that runs strictly within that section: Train 3.

Sample Input 3

10 10 10
1 6
2 9
4 5
4 7
4 7
5 8
6 6
6 7
7 9
10 10
1 8
1 9
1 10
2 8
2 9
2 10
3 8
3 9
3 10
1 10

Sample Output 3

7
9
10
6
8
9
6
7
8
10

Solution in C# (Mono 4.6.2.0) (judge verdict: Time Limit Exceeded)

using System;
using System.Collections.Generic;
using System.Linq;
using static System.Console;
using static System.Int32;

class Program
{
    class Train
    {
        public int Left;
        public List<int> Rights = new List<int>();
    }

    static void Main(string[] args)
    {
        var list = new List<Train>();
        var nums = ReadLine().Split();
        int tCount = Parse(nums[1]);
        int qCount = Parse(nums[2]);
        for (int i = 0; i < tCount; ++i)
        {
            nums = ReadLine().Split();
            AddTrain(list, Parse(nums[0]), Parse(nums[1]));
        }
        list.Sort((t1, t2) => t1.Left - t2.Left);
        foreach (var t in list)
        {
            t.Rights.Sort();
        }
        for(int i = 0; i < qCount; ++i)
        {
            nums = ReadLine().Split();
            int left = Parse(nums[0]);
            int right = Parse(nums[1]);
            int result = 0;
            for(int j = FirstIndex(list, t => left <= t.Left); j < list.Count; ++j)
            {
                var tr = list[j];
                var count = FirstIndex(tr.Rights, r => right < r);
                result += count;
            }
            WriteLine(result);
        }
    }

    static void AddTrain(List<Train> list, int left, int right)
    {
        var tr = list.Find(t => t.Left == left);
        if (tr == null)
        {
            tr = new Train() { Left = left };
            list.Add(tr);
        }
        tr.Rights.Add(right);
    }

    public static int FirstIndex<T>(List<T> arr, Func<T,bool> func)
    {
        int low = 0;
        int high = arr.Count;
        int mid;
        while (low < high)
        {
            mid = ((high - low) >> 1) + low;
            if (func(arr[mid])) high = mid;
            else low = mid + 1;
        }
        return low;
    }
}