Siblings of Parent

Siblings of Parent: N lines containing two integers each representing the parent and child nodes of a tree are given as input to the program. Also, M integers are passed as input to the program. For each integer among M integers, the program must print the siblings of the parent as the output.
Note: The siblings must be printed in the order of their occurrence.

Boundary Condition(s):
1 <= N <= 1000
1 <= M <= 800

Input Format:
The first line contains N.
The next N lines contain two integers (parent and child) separated by space(s).
The (N+2)^th line contains the value of M
The (N+3)^th line contains M integers separated by space(s).

Output Format:
The first M lines contain the siblings of the parent of each node represented by M integers (one for each line).

Example Input/Output 1:
Input:
9
4 2
4 34
2 12
2 3
34 44
34 40
4 23
23 60
3 78
2
78 40

Output:
12
2 23

Explanation:
The tree formed is given below.

The parent of 78 is 3 and its sibling is 12.
The parent of 40 is 34 and its siblings are 2 and 23.

Example Input/Output 2:
Input:
11
5 6
2 3
5 2
3 56
5 8
5 7
6 89
89 54
89 63
89 52
52 69
3
69 89 3

Output:
54 63
2 8 7
6 8 7

#include <stdio.h>
int main() {
  int k, n;
  scanf("%d", & k);
  int mat[k][2];
  for (int i = 0; i < k; i++)
    scanf("%d%d", & mat[i][0], & mat[i][1]);
  scanf("%d", & n);
  int a[n];
  for (int i = 0; i < n; i++)
    scanf("%d", & a[i]);
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < k; j++) {
      if (a[i] == mat[j][1]) {
        for (int l = 0; l < k; l++) {
          if (mat[j][0] == mat[l][1]) {
            for (int p = 0; p < k; p++) {
              if (mat[p][0] == mat[l][0] && p != l)
                printf("%d ", mat[p][1]);
            }
            printf("n");
            break;
          }
        }
        break;
      }
    }
  }
}