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 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <stdio.h>
#include <stdlib.h>

typedef struct { int l, r; } train;

int train_sort(const void *a, const void *b){
  train *A = (train *)a, *B = (train *)b;
  return A->l - B->l;
}

int
main(int argc, char *argv[])
{
  int n, m, Q;
  train tr[200000];
  scanf("%d %d %d", &n, &m, &Q);
  for(int i = 0; i < m; i++){
    scanf("%d %d", &tr[i].l, &tr[i].r);
  }
  qsort(tr, m, sizeof(tr[0]), train_sort);

  int p, q, ans;
  for(int i = 0; i < Q; i++){
    scanf("%d %d", &p, &q);
    ans = 0;
    if(tr[m - 1].r < p) printf("0\n");
    else{
      int l = -1, r = m - 1;
      while(r - l > 1){
	if(tr[(r + l) / 2].l >= p) r = (r + l) / 2;
	else l = (r + l) / 2;
      }
      for(int j = r; j < m; j++){
	if(tr[j].r <= q) ans++;
      }
      printf("%d\n", ans);
    }
  }

  return 0;
}