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 x = 0, f = 1;
  char c = getchar();
  while (!isdigit(c)) {
    if (c == '-') f = -1;
    c = getchar();
  }
  while (isdigit(c)) {
    x = x * 10 + c - '0';
    c = getchar();
  }
  return x * f;
}
int r, c, n;
bool has[3010][3010 << 1];
int fa[9000010 << 1];
int findset(int x) { return x == fa[x] ? x : fa[x] = findset(fa[x]); }
int main() {
  r = read();
  c = (read() << 1);
  n = read();
  for (int i = 0; i <= r * c + 1; i++) fa[i] = i;
  int s = r * c, t = s + 1;
  int ans = 0;
  for (int i = 1; i <= n; i++) {
    int x = read() - 1, y = read() - 1, a = x * c + y, b = x * c + y + (c >> 1);
    has[x][y] = has[x][y + (c >> 1)] = 1;
    int ns[20], tp[20], cnt = 0;
    memset(tp, 0, sizeof(tp));
    if (x) {
      if (y < c && has[x - 1][y + 1])
        ns[++cnt] = (x - 1) * c + y + 1, tp[cnt] += 1;
      if (y && has[x - 1][y - 1]) ns[++cnt] = (x - 1) * c + y - 1, tp[cnt] += 1;
    }
    if (y < c && has[x][y + 1]) ns[++cnt] = x * c + y + 1, tp[cnt] += 1;
    if (y && has[x][y - 1]) ns[++cnt] = x * c + y - 1, tp[cnt] += 1;
    if (x < r - 1) {
      if (y < c && has[x + 1][y + 1])
        ns[++cnt] = (x + 1) * c + y + 1, tp[cnt] += 1;
      if (y && has[x + 1][y - 1]) ns[++cnt] = (x + 1) * c + y - 1, tp[cnt] += 1;
    }
    y += (c >> 1);
    if (x) {
      if (y < c && has[x - 1][y + 1])
        ns[++cnt] = (x - 1) * c + y + 1, tp[cnt] += 2;
      if (y && has[x - 1][y - 1]) ns[++cnt] = (x - 1) * c + y - 1, tp[cnt] += 2;
    }
    if (y < c && has[x][y + 1]) ns[++cnt] = x * c + y + 1, tp[cnt] += 2;
    if (y && has[x][y - 1]) ns[++cnt] = x * c + y - 1, tp[cnt] += 2;
    if (x < r - 1) {
      if (y < c && has[x + 1][y + 1])
        ns[++cnt] = (x + 1) * c + y + 1, tp[cnt] += 2;
      if (y && has[x + 1][y - 1]) ns[++cnt] = (x + 1) * c + y - 1, tp[cnt] += 2;
    }
    y -= (c >> 1);
    bool S = 0, T = 0;
    for (int i = 1; i <= cnt; i++) {
      int u = findset(ns[i]);
      if (u == findset(s)) S = 1;
      if (u == findset(t)) T = 1;
    }
    if (!y) S = 1;
    if (y + (c >> 1) == c - 1) T = 1;
    if (!S || !T) {
      ans++;
      bool hs = 0;
      int p1 = -1, p2 = -1;
      for (int i = 1; i <= cnt; i++) {
        for (int j = 1; j <= cnt; j++)
          if (tp[i] == tp[j] || tp[i] == 3 || tp[j] == 3) {
            int u = findset(ns[i]), v = findset(ns[j]);
            if (u != v) fa[v] = u;
          }
        if (tp[i] == 1 || tp[i] == 3) p1 = i;
        if (tp[i] == 2 || tp[i] == 3) p2 = i;
      }
      if (cnt) {
        int u, v;
        if (p1 >= 0) {
          u = findset(ns[p1]), v = findset(a);
          if (u != v) fa[v] = u;
        }
        if (p2 >= 0) {
          u = findset(ns[p2]);
          v = findset(b);
          if (u != v) fa[v] = u;
        }
      }
      if (!y) {
        int u = findset(a), v = findset(s);
        if (u != v) fa[v] = u;
      }
      if (y + (c >> 1) == c - 1) {
        int u = findset(b), v = findset(t);
        if (u != v) fa[v] = u;
      }
    } else
      has[x][y] = has[x][y + (c >> 1)] = 0;
  }
  printf("%d\n", ans);
  return 0;
}
