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>
const int maxn = 3001, dx[] = {-1, 0, 1, -1, 1, -1, 0, 1},
          dy[] = {-1, -1, -1, 0, 0, 1, 1, 1};
int r, c, n, fa[maxn * maxn * 2], ans;
bool vis[maxn][maxn * 2];
int find(int x) { return x == fa[x] ? x : fa[x] = find(fa[x]); }
int main() {
  scanf("%d%d%d", &r, &c, &n);
  if (c == 1) {
    puts("0");
    return 0;
  }
  for (int i = 0; i < r * c * 2; ++i) fa[i] = i;
  while (n--) {
    int x, y;
    bool flag = 0;
    scanf("%d%d", &x, &y);
    --x, --y;
    for (int i = 0; i < 8; ++i) {
      int x1 = x + dx[i], y1 = y + dy[i];
      if (x1 < 0 || x1 >= c * 2) continue;
      if (y1 < 0) y1 = c * 2 - 1;
      if (!vis[x1][y1]) continue;
      for (int j = 0; j < 8; ++j) {
        int x2 = x + dx[j], y2 = y + c + dy[j];
        if (x2 < 0 || x2 >= c * 2) continue;
        if (y2 >= c * 2) y2 = 0;
        if (!vis[x2][y2]) continue;
        if (find(x1 * c * 2 + y1) == find(x2 * c * 2 + y2)) {
          flag = 1;
          break;
        }
      }
      if (flag) break;
    }
    if (!flag) {
      ++ans;
      vis[x][y] = vis[x][y + c] = 1;
      for (int i = 0; i < 8; ++i) {
        int x1 = x + dx[i], y1 = y + dy[i];
        if (x1 < 0 || x1 >= c * 2) continue;
        if (y1 < 0) y1 = c * 2 - 1;
        if (vis[x1][y1]) fa[find(x * c * 2 + y)] = find(x1 * c * 2 + y1);
      }
      for (int i = 0; i < 8; ++i) {
        int x1 = x + dx[i], y1 = y + c + dy[i];
        if (x1 < 0 || x1 >= c * 2) continue;
        if (y1 >= c * 2) y1 = 0;
        if (vis[x1][y1]) fa[find(x * c * 2 + y + c)] = find(x1 * c * 2 + y1);
      }
    }
  }
  printf("%d\n", ans);
  return 0;
}
