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;

class Program
{
	public static int Main(string[] args)
	{
        
        string[] str = Console.ReadLine().Split(' ');
        int n = int.Parse(str[0]);
        int m = int.Parse(str[1]);
        int q = int.Parse(str[2]);
        List<short[]> lr_list = new List<short[]>();
        for (int i = 0; i < m;i++){
            str = Console.ReadLine().Split(' ');
            lr_list.Add(new short[] { short.Parse(str[0]), short.Parse(str[1])});
        }
        List<short[]> pq_list = new List<short[]>();
        for (int i = 0; i < q; i++)
        {
            str = Console.ReadLine().Split(' ');
            pq_list.Add(new short[] { short.Parse(str[0]), short.Parse(str[1]) });
        }

        List<int> answer = new List<int>();
        List<int> answer_index = new List<int>();
        for (int i = 0; i < q;i++){
            answer_index.Clear();
            for (int j = 0; j < m;j++){
                answer_index.Add(j);
            }
            short pi = pq_list[i][0];
            short qi = pq_list[i][1];

            for (int j = answer_index.Count - 1; j >= 0; j--){
                if(pi > lr_list[answer_index[j]][0] || qi < lr_list[answer_index[j]][1]){
                    answer_index.RemoveAt(j);
                }
            }

            answer.Add(answer_index.Count);
        }
        for (int i = 0; i < answer.Count;i++){
            Console.WriteLine(answer[i]);   
        }
		return 0;
	}
}