2 5 10
2 2
1 1
1 4
2 1
1 2
1 5
2 4
2 5
1 3
2 3
 2 2 2
1 1
2 2
 3 3 9
1 1
1 2
1 3
2 1
2 2
2 3
3 1
3 2
3 3
 7 5 35
5 3
3 5
1 1
2 5
6 4
7 2
5 1
3 4
6 5
7 3
4 1
2 2
4 2
2 4
4 3
3 3
6 1
1 2
4 5
1 3
2 1
5 5
7 5
7 1
6 2
1 4
1 5
3 2
4 4
5 2
2 3
6 3
7 4
5 4
3 1
 1 5 4
1 1
1 2
1 4
1 5
 1 1 1
1 1
 5 7 21
4 4
4 5
5 5
5 6
5 7
5 1
5 2
4 2
3 2
3 1
3 7
3 6
2 6
1 6
1 7
1 1
1 2
1 3
1 4
2 4
3 4
 2 1 1
1 1
 2 2 4
2 1
1 1
1 2
2 2
 3000 3000 1
2222 738
 5 7 35
1 2
2 3
5 1
5 7
4 4
5 3
3 1
2 6
4 5
2 7
4 1
2 1
2 2
1 7
5 6
3 6
4 6
1 6
1 1
3 3
3 4
4 2
2 5
5 5
3 5
2 4
1 5
1 3
4 3
5 4
1 4
3 7
4 7
3 2
5 2
 5 4 1
4 1
 3 4 12
2 3
3 2
2 2
2 1
1 2
3 1
1 4
1 3
3 3
2 4
3 4
1 1
 3 3 3
1 1
2 2
3 3

8
 1
 6
 26
 4
 0
 20
 0
 2
 1
 28
 1
 9
 3

#include <bits/stdc++.h>
using namespace std;
int r, c, n;
int pre[3005 * 3005];
void init() {
  for (int i = 1; i <= 3000 * 3000; i++) pre[i] = i;
}
int find(int x) {
  if (pre[x] != x) {
    pre[x] = find(pre[x]);
  }
  return pre[x];
}
void Union(int x, int y) {
  int fx = find(x);
  int fy = find(y);
  pre[fx] = fy;
}
bool cl[3005 * 3005];
bool cr[3005 * 3005];
bool has[3005][3005];
bool intable(int x, int y) {
  if (x >= 0 && x < r && y >= 0 && y < c) return true;
  return false;
}
int dx[8] = {-1, -1, 0, 1, 1, 1, 0, -1};
int dy[8] = {0, 1, 1, 1, 0, -1, -1, -1};
bool check(int x, int y) {
  bool L = false, R = false;
  if (y == 0) L = true;
  if (y == c - 1) R = true;
  for (int i = 0; i < 8; i++) {
    int nx = x + dx[i];
    int ny = y + dy[i];
    if (intable(nx, ny)) {
      int pos = nx * c + ny;
      L |= cl[find(pos)];
      R |= cr[find(pos)];
    }
  }
  if (L && R)
    return true;
  else {
    int pos = x * c + y;
    for (int i = 0; i < 8; i++) {
      int nx = x + dx[i];
      int ny = y + dy[i];
      if (intable(nx, ny) && has[nx][ny]) {
        int ppos = nx * c + ny;
        if (find(pos) != find(ppos)) Union(pos, ppos);
      }
    }
    cl[find(pos)] |= L;
    cr[find(pos)] |= R;
    has[x][y] = 1;
    return false;
  }
}
int main() {
  scanf("%d%d%d", &r, &c, &n);
  int cnt = 0;
  init();
  for (int i = 0; i < n; i++) {
    int x, y;
    scanf("%d%d", &x, &y);
    x--;
    y--;
    if (!check(x, y)) cnt++;
  }
  printf("%d\n", cnt);
  return 0;
}
