#include <bits/stdc++.h>
using namespace std;
const int N = 3011;
const long long oo = 1e17 + 11;
int tcases = 1;
int m, n, q;
bool marked[N][N * 2];
struct {
  int g[N * N * 2], rank[N * N * 2];
  vector<pair<int, int> > his;
  int getId(int x, int y) { return (x - 1) * 2 * n + y; }
  void init() {
    for (int i = 1; i <= m * n * 2; ++i) {
      g[i] = i;
      rank[i] = 1;
    }
  }
  int find(int i) { return i == g[i] ? i : find(g[i]); }
  void join(int i, int j) {
    i = find(i);
    j = find(j);
    if (i != j) {
      his.push_back(make_pair(i, rank[i]));
      his.push_back(make_pair(j, rank[j]));
      if (rank[i] > rank[j]) swap(i, j);
      g[i] = j;
      if (rank[j] == rank[i]) ++rank[j];
    }
  }
  void rollback() {
    while (his.size()) {
      rank[his.back().first] = his.back().second;
      g[his.back().first] = his.back().first;
      his.pop_back();
    }
  }
  int cal(int x, int y) {
    for (int t = 1; t <= 2; ++t) {
      int d = t >= 2 ? n : 0;
      int u = getId(x, y + d);
      for (int i = -1; i <= 1; ++i)
        for (int j = -1; j <= 1; ++j)
          if (i != 0 || j != 0) {
            int x0 = x + i, y0 = y + d + j;
            if (y0 < 1) y0 = 2 * n;
            if (y0 > 2 * n) y0 = 1;
            if (1 <= x0 && x0 <= m && marked[x0][y0]) {
              join(u, getId(x0, y0));
            }
          }
    }
    if (find(getId(x, y)) == find(getId(x, y + n))) {
      rollback();
      return 0;
    }
    his.clear();
    marked[x][y] = marked[x][y + n] = 1;
    return 1;
  }
} Dsu;
void testcase() {
  cin >> m >> n >> q;
  if (n <= 1) {
    cout << 0;
    return;
  }
  Dsu.init();
  int res = 0;
  for (int i = 1; i <= q; ++i) {
    int x, y;
    cin >> x >> y;
    res += Dsu.cal(x, y);
  }
  cout << res;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie();
  cout.tie();
  for (int i = 1; i <= tcases; ++i) testcase();
  cerr << "\nTime elapsed: " << 1000 * clock() / CLOCKS_PER_SEC << "ms\n";
  return 0;
}
