#include <bits/stdc++.h>
using namespace std;
const int N = 1e6 + 50;
int T, n, m, q, col[N * 30], f[N * 30];
int dx[9] = {0, 0, 0, 1, -1, 1, -1, 1, -1};
int dy[9] = {0, -1, 1, 0, 0, 1, -1, -1, 1};
int calc(int x, int y) { return (x - 1) * 2 * m + y; }
int find(int x) {
  if (x == f[x])
    return x;
  else
    return f[x] = find(f[x]);
}
int main() {
  int ans = 0;
  scanf("%d%d%d", &n, &m, &q);
  for (int i = 1; i <= n * m * 2; i++) f[i] = i;
  if (m == 1) {
    puts("0");
    return 0;
  }
  for (int i = 1; i <= q; i++) {
    int xx, yy;
    scanf("%d%d", &xx, &yy);
    int fx = find(calc(xx, yy)), ffx = find(calc(xx, yy + m));
    bool flag = true;
    for (int i = 1; i <= 8; i++) {
      if (!flag) break;
      int tx = xx + dx[i], ty = yy + dy[i];
      if (tx > n || tx < 1) continue;
      if (ty < 1)
        ty = 2 * m;
      else if (ty > 2 * m)
        ty = 1;
      if (!col[calc(tx, ty)]) continue;
      for (int j = 1; j <= 8; j++) {
        int ttx = xx + dx[j], tty = yy + m + dy[j];
        if (ttx > n || ttx < 1) continue;
        if (tty < 1)
          tty = 2 * m;
        else if (tty > 2 * m)
          tty = 1;
        if (!col[calc(ttx, tty)]) continue;
        int ft = find(calc(tx, ty)), fft = find(calc(ttx, tty));
        if (ft == fft) {
          flag = false;
          break;
        }
      }
    }
    if (flag) {
      col[calc(xx, yy)] = 1;
      col[calc(xx, yy + m)] = 1;
      for (int i = 1; i <= 8; i++) {
        int tx = xx + dx[i], ty = yy + dy[i];
        int ttx = xx + dx[i], tty = yy + m + dy[i];
        if (!(tx > n || tx < 1)) {
          if (ty < 1)
            ty = 2 * m;
          else if (ty > 2 * m)
            ty = 1;
          if (col[calc(tx, ty)]) f[find(calc(tx, ty))] = fx;
        }
        if (!(ttx > n || ttx < 1)) {
          if (tty < 1)
            tty = 2 * m;
          else if (tty > 2 * m)
            tty = 1;
          if (col[calc(ttx, tty)]) f[find(calc(ttx, tty))] = ffx;
        }
      }
      ans++;
    }
  }
  printf("%d\n", ans);
  return 0;
}
