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;
const int maxn = 3000 * 3000 * 2 + 100;
const int dx[8] = {-1, -1, -1, 0, 0, 1, 1, 1};
const int dy[8] = {-1, 0, 1, -1, 1, -1, 0, 1};
int n, r, c;
int ans;
int fa[maxn];
bool vis[3010][6010];
int q[2][10];
int find(int cur) {
  if (fa[cur] < 0)
    return cur;
  else
    return (find(fa[cur]));
}
void Union(int u, int v) {
  u = find(u);
  v = find(v);
  if (u == v) return;
  if (fa[u] > fa[v]) swap(u, v);
  fa[u] += fa[v];
  fa[v] = u;
}
void merge(int x, int y) {
  int nid = (x - 1) * c + y;
  for (int i = 0; i < 8; ++i) {
    int x1 = x + dx[i];
    int y1 = y + dy[i];
    if (x1 < 1 || y1 < 1 || x1 > r || y1 > c || !vis[x1][y1]) continue;
    Union(nid, (x1 - 1) * c + y1);
  }
}
void get_list(int x, int y, int id) {
  q[id][0] = 0;
  for (int i = 0; i < 8; ++i) {
    int x1 = x + dx[i];
    int y1 = y + dy[i];
    if (x1 < 1 || y1 < 1 || x1 > r || y1 > c || !vis[x1][y1]) continue;
    q[id][++q[id][0]] = find((x1 - 1) * c + y1);
  }
}
void solve() {
  c *= 2;
  for (int i = 1; i <= r; ++i)
    for (int j = 1; j <= c; ++j) fa[(i - 1) * c + j] = -1;
  for (int i = 1; i <= n; ++i) {
    int x, y;
    scanf("%d%d", &x, &y);
    get_list(x, y, 0);
    get_list(x, y + c / 2, 1);
    bool flag = true;
    for (int j = 1; j <= q[0][0]; ++j)
      for (int k = 1; k <= q[1][0]; ++k)
        if (q[0][j] == q[1][k]) {
          flag = false;
          break;
        }
    if (!flag) continue;
    ++ans;
    merge(x, y);
    merge(x, y + c / 2);
    vis[x][y] = true;
    vis[x][y + c / 2] = true;
  }
}
int main() {
  scanf("%d%d%d", &r, &c, &n);
  solve();
  printf("%d\n", ans);
  return 0;
}
