#include <bits/stdc++.h>
using namespace std;
const int N = 3005;
bool f[N][N * 2];
int n, m, fa[N * N * 2], cnt[N * N * 2];
int dx[8] = {-1, -1, -1, 0, 0, 1, 1, 1};
int dy[8] = {-1, 0, 1, -1, 1, -1, 0, 1};
inline int ID(int x, int y) { return (x - 1) * m * 2 + y; }
void init() {
  for (int i = 1; i <= n * m * 2; i++) fa[i] = i;
}
int father(int x) { return x == fa[x] ? x : fa[x] = father(fa[x]); }
void comb(int x, int y) {
  x = father(x);
  y = father(y);
  if (x == y) return;
  if (cnt[x] < cnt[y]) {
    fa[x] = y;
    cnt[y] += cnt[x];
  } else {
    fa[y] = x;
    cnt[x] += cnt[y];
  }
}
bool ok(int x, int y) {
  vector<pair<int, int> > vx[2];
  pair<int, int> v[2] = {make_pair(x, y), make_pair(x, y + m)};
  for (int i = 0; i < 2; i++) {
    for (int j = 0; j < 8; j++) {
      int xx = v[i].first + dx[j], yy = v[i].second + dy[j];
      yy = (yy - 1 + 2 * m) % (2 * m) + 1;
      if (xx >= 1 && xx <= n && yy >= 1 && yy <= m * 2 && f[xx][yy])
        vx[i].push_back(make_pair(xx, yy));
    }
  }
  for (int i = 0; i < vx[0].size(); i++) {
    for (int j = 0; j < vx[1].size(); j++) {
      if (father(ID(vx[0][i].first, vx[0][i].second)) ==
          father(ID(vx[1][j].first, vx[1][j].second)))
        return 0;
    }
  }
  f[x][y] = f[x][y + m] = 1;
  for (int i = 0; i < vx[0].size(); i++)
    comb(ID(x, y), ID(vx[0][i].first, vx[0][i].second));
  for (int i = 0; i < vx[1].size(); i++)
    comb(ID(x, y + m), ID(vx[1][i].first, vx[1][i].second));
  return 1;
}
int main() {
  int K, ans = 0;
  scanf("%d%d%d", &n, &m, &K);
  init();
  while (K--) {
    int x, y;
    scanf("%d%d", &x, &y);
    ans += ok(x, y);
  }
  if (m == 1) ans = 0;
  printf("%d\n", ans);
  return 0;
}
