#include <bits/stdc++.h>
using namespace std;
const int dx[8] = {0, 0, -1, -1, -1, 1, 1, 1};
const int dy[8] = {-1, 1, -1, 0, 1, -1, 0, 1};
int r, c, n, res, a, b, f[18000005];
bool vis[3001][6001], g[3001][6001];
stack<pair<int, int> > stk;
void init() {
  for (int i = 0; i < r * c; ++i) f[i] = i;
}
int F(int x) {
  if (f[x] == x) return x;
  stk.push(pair<int, int>(x, f[x]));
  return f[x] = F(f[x]);
}
void U(int a, int b) {
  int fa = F(a), fb = F(b);
  stk.push(pair<int, int>(fa, f[fa]));
  f[fa] = fb;
}
int main() {
  scanf("%d%d%d", &r, &c, &n);
  c <<= 1;
  init();
  for (int i = 0; i < n; ++i) {
    scanf("%d%d", &a, &b);
    --a;
    --b;
    while (!stk.empty()) stk.pop();
    vis[a][b] = vis[a][b + c / 2] = true;
    for (int i = 0; i < 8; ++i) {
      int tx = a + dx[i], ty = b + dy[i];
      if (ty == -1) ty = c - 1;
      if (ty == c) ty = 0;
      if (tx < 0 || tx >= r || !vis[tx][ty]) continue;
      U(tx * c + ty, a * c + b);
    }
    b += c / 2;
    for (int i = 0; i < 8; ++i) {
      int tx = a + dx[i], ty = b + dy[i];
      if (ty == -1) ty = c - 1;
      if (ty == c) ty = 0;
      if (tx < 0 || tx >= r || !vis[tx][ty]) continue;
      U(tx * c + ty, a * c + b);
    }
    b -= c / 2;
    if (F(a * c + b) == F(a * c + b + c / 2)) {
      vis[a][b] = vis[a][b + c / 2] = false;
      while (!stk.empty()) {
        f[stk.top().first] = stk.top().second;
        stk.pop();
      }
    } else {
      vis[a][b] = vis[a][b + c / 2] = true;
      ++res;
    }
  }
  printf("%d\n", res);
  return 0;
}
