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 fa[3010 * 6010];
int find(int x) {
  if (fa[x] != x) fa[x] = find(fa[x]);
  return fa[x];
}
int ax[8] = {-1, -1, -1, 0, 0, 1, 1, 1};
int ay[8] = {-1, 0, 1, -1, 1, -1, 0, 1};
int n, m, Q;
bool inside(int x, int &y) {
  if (x < 0 || x >= n) return false;
  if (y == -1) y = m + m - 1;
  if (y == m + m) y = 0;
  return true;
}
int get_id(int x, int y) { return x * m * 2 + y; }
void uunion(int x, int y) {
  int fx = find(x);
  int fy = find(y);
  if (fx != fy) fa[fx] = fy;
}
bool vis[3010 * 6010];
int main() {
  scanf("%d %d %d", &n, &m, &Q);
  for (int i = 0; i < 3010 * 6010; i++) fa[i] = i;
  memset(vis, false, sizeof(vis));
  int ans = 0;
  while (Q--) {
    int x1, y1, x2, y2;
    scanf("%d %d", &x1, &y1);
    if (m == 1) continue;
    x1--;
    y1--;
    if (vis[get_id(x1, y1)]) continue;
    if (n == 1) {
      if (ans == m - 1) continue;
      vis[get_id(x1, y1)] = true;
      ans++;
      continue;
    }
    x2 = x1;
    y2 = y1 + m;
    bool ok = true;
    for (int k1 = 0; k1 < 8; k1++) {
      int xx1 = x1 + ax[k1];
      int yy1 = y1 + ay[k1];
      if (!inside(xx1, yy1)) continue;
      if (!vis[get_id(xx1, yy1)]) continue;
      for (int k2 = 0; k2 < 8; k2++) {
        int xx2 = x2 + ax[k2];
        int yy2 = y2 + ay[k2];
        if (!inside(xx2, yy2)) continue;
        if (!vis[get_id(xx2, yy2)]) continue;
        int fx = find(get_id(xx1, yy1));
        int fy = find(get_id(xx2, yy2));
        if (fx == fy) {
          ok = false;
        }
      }
    }
    if (ok) {
      vis[get_id(x1, y1)] = true;
      vis[get_id(x2, y2)] = true;
      ans++;
      for (int k1 = 0; k1 < 8; k1++) {
        int xx1 = x1 + ax[k1];
        int yy1 = y1 + ay[k1];
        if (!inside(xx1, yy1)) continue;
        if (!vis[get_id(xx1, yy1)]) continue;
        uunion(get_id(x1, y1), get_id(xx1, yy1));
      }
      for (int k2 = 0; k2 < 8; k2++) {
        int xx2 = x2 + ax[k2];
        int yy2 = y2 + ay[k2];
        if (!inside(xx2, yy2)) continue;
        if (!vis[get_id(xx2, yy2)]) continue;
        uunion(get_id(x2, y2), get_id(xx2, yy2));
      }
    }
  }
  printf("%d\n", ans);
  return 0;
}
