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 * 6005];
void init() {
  for (int i = 1; i <= 3000 * 6000; 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 * 6005];
bool cr[3005 * 6005];
bool has[3005][6005];
bool intable(int x, int y) {
  if (x >= 0 && x < r && y >= 0 && y < c + 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;
  bool R = false;
  if (y == 0) L = true;
  if (y == 2 * 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)) {
      L |= cl[find(nx * c * 2 + ny)];
      R |= cr[find(nx * c * 2 + ny)];
    }
  }
  return L && R;
}
bool check(int x1, int y1, int x2, int y2) {
  bool L = false, R = false, mid = false;
  bool rL = false, lR = false;
  if (y1 == 0) L = true;
  if (y2 == 2 * c - 1) R = true;
  for (int i = 0; i < 8; i++) {
    int nx = x1 + dx[i];
    int ny = y1 + dy[i];
    if (intable(nx, ny)) {
      L |= cl[find(nx * c * 2 + ny)];
      rL |= cr[find(nx * c * 2 + ny)];
    }
  }
  for (int i = 0; i < 8; i++) {
    int nx = x2 + dx[i];
    int ny = y2 + dy[i];
    if (intable(nx, ny)) {
      R |= cr[find(nx * c * 2 + ny)];
      lR |= cl[find(nx * c * 2 + ny)];
    }
  }
  for (int i = 0; i < 8; i++) {
    for (int j = 0; j < 8; j++) {
      int nx1 = x1 + dx[i], ny1 = y1 + dy[i];
      int nx2 = x2 + dx[j], ny2 = y2 + dy[j];
      if (intable(nx1, ny1) && intable(nx2, ny2) && has[nx1][ny1] &&
          has[nx2][ny2]) {
        if (find(nx1 * c * 2 + ny1) == find(nx2 * c * 2 + ny2)) mid = true;
      }
    }
  }
  if (L && R && mid) return true;
  for (int i = 0; i < 8; i++) {
    int nx = x1 + dx[i];
    int ny = y1 + dy[i];
    if (intable(nx, ny) && has[nx][ny]) Union(x1 * c * 2 + y1, nx * c * 2 + ny);
  }
  cl[find(x1 * c * 2 + y1)] |= L;
  cr[find(x1 * c * 2 + y1)] |= rL;
  for (int i = 0; i < 8; i++) {
    int nx = x2 + dx[i];
    int ny = y2 + dy[i];
    if (intable(nx, ny) && has[nx][ny]) Union(x2 * c * 2 + y2, nx * c * 2 + ny);
  }
  cl[find(x2 * c * 2 + y2)] |= lR;
  cr[find(x2 * c * 2 + y2)] |= R;
  has[x1][y1] = true;
  has[x2][y2] = true;
  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)) continue;
    if (check(x, y + c)) continue;
    if (!check(x, y, x, y + c)) cnt++;
  }
  if (c == 1) {
    printf("0\n");
    return 0;
  }
  printf("%d\n", cnt);
  return 0;
}
