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 Read() {
  int i = 0, f = 1;
  char ch = 0;
  while (!isdigit(ch) && ch != '-') ch = getchar();
  if (ch == '-') ch = getchar(), f = -1;
  while (isdigit(ch)) i = (i << 1) + (i << 3) + ch - 48, ch = getchar();
  return i * f;
}
const int N = 2e7 + 5;
const int M = 3e3 + 5;
const int dx[] = {1, 1, 1, 0, 0, -1, -1, -1};
const int dy[] = {1, 0, -1, 1, -1, 1, 0, -1};
int r, c, n, cnt;
int fa[N], id[M][M << 1];
bool del[M][M << 1];
int v[10];
int get(int x) { return x == fa[x] ? x : fa[x] = get(fa[x]); }
bool chk(int x, int y) {
  int xx = x, yy = y + c;
  cnt = 0;
  for (int i = 1; i <= 8; ++i) v[i] = 0;
  for (int i = 0; i < 8; ++i) {
    int nx = x + dx[i], ny = y + dy[i];
    if (nx <= 0 || nx > r) continue;
    if (ny == c + c + 1) ny = 1;
    if (ny == 0) ny = c + c;
    if (del[nx][ny]) v[++cnt] = get(id[nx][ny]);
  }
  for (int i = 0; i < 8; ++i) {
    int nx = xx + dx[i], ny = yy + dy[i];
    if (nx <= 0 || nx > r) continue;
    if (ny == c + c + 1) ny = 1;
    if (ny == 0) ny = c + c;
    if (del[nx][ny]) {
      int p = get(id[nx][ny]);
      for (int i = 1; i <= cnt; ++i)
        if (p == v[i]) return false;
    }
  }
  return true;
}
void merge(int x, int y) {
  del[x][y] = true;
  for (int i = 0; i < 8; ++i) {
    int nx = x + dx[i], ny = y + dy[i];
    if (nx <= 0 || nx > r) continue;
    if (ny == c + c + 1) ny = 1;
    if (ny == 0) ny = c + c;
    if (del[nx][ny]) {
      int a = get(id[nx][ny]), b = get(id[x][y]);
      if (a == b) continue;
      fa[a] = b;
    }
  }
}
int main() {
  r = Read(), c = Read(), n = Read();
  if (c == 1) {
    puts("0");
    return 0;
  }
  for (int i = 1; i <= r; ++i)
    for (int j = 1; j <= c * 2; ++j) id[i][j] = ++cnt, fa[cnt] = cnt;
  int ans = 0;
  for (int i = 1; i <= n; ++i) {
    int x = Read(), y = Read();
    if (!chk(x, y)) continue;
    merge(x, y);
    merge(x, y + c);
    ++ans;
  }
  cout << ans << '\n';
  return 0;
}
