#include <bits/stdc++.h>
using namespace std;
const int N = 3003 * 6006;
const int qwq = 303030;
const int inf = 0x3f3f3f3f;
int n, m, k;
int f[N], fa[N], st[123], cnt;
int ans;
int ff[] = {1, 1, 1, 0, -1, -1, -1, 0};
int gg[] = {1, 0, -1, -1, -1, 0, 1, 1};
inline int read() {
  int sum = 0, f = 1;
  char c = getchar();
  while (c < '0' || c > '9') {
    if (c == '-') f = -1;
    c = getchar();
  }
  while (c >= '0' && c <= '9') {
    sum = sum * 10 + c - '0';
    c = getchar();
  }
  return sum * f;
}
inline int dian(int x, int y) {
  if (y == 0) y = 2 * m;
  if (y == 2 * m + 1) y = 1;
  return (x - 1) * (m << 1) + y;
}
int find(int u) {
  while (fa[u] != u) u = fa[u];
  return u;
}
int Splay(int u) { return fa[u] == u ? u : fa[u] = Splay(fa[u]); }
int main() {
  int x, y;
  n = read();
  m = read();
  k = read();
  if (m == 1) {
    cout << 0;
    return 0;
  }
  for (int i = 1; i <= n * m * 2; i++) fa[i] = i;
  while (k--) {
    cnt = 0;
    x = read();
    y = read();
    for (int i = 0; i <= 8; i++) {
      if (x + ff[i] < 1 || x + ff[i] > n) continue;
      int u = dian(x + ff[i], y + gg[i]);
      if (!f[u]) continue;
      int aa = find(u);
      int bb = find(dian(x, y));
      if (aa == bb) continue;
      st[++cnt] = bb;
      fa[bb] = aa;
    }
    y += m;
    for (int i = 0; i < 8; i++) {
      if (x + ff[i] < 1 || x + ff[i] > n) continue;
      int u = dian(x + ff[i], y + gg[i]);
      if (!f[u]) continue;
      int aa = find(u);
      int bb = find(dian(x, y));
      if (aa == bb) continue;
      st[++cnt] = bb;
      fa[bb] = aa;
    }
    y -= m;
    if (find(dian(x, y)) != find(dian(x, y + m))) {
      ans++;
      for (int i = 0; i < 8; i++) {
        if (x + ff[i] < 1 || x + ff[i] > n) continue;
        Splay(dian(x + ff[i], y + gg[i]));
      }
      y += m;
      for (int i = 0; i < 8; i++) {
        if (x + ff[i] < 1 || x + ff[i] > n) continue;
        Splay(dian(x + ff[i], y + gg[i]));
      }
      y -= m;
      f[dian(x, y)] = f[dian(x, y + m)] = 1;
    } else {
      for (int i = 1; i <= cnt; i++) fa[st[i]] = st[i];
    }
  }
  cout << ans;
  return 0;
}
