#include <bits/stdc++.h>
using namespace std;
const int N = 2e7 + 5;
const int dx[] = {-1, 0, 1, -1, 1, -1, 0, 1},
          dy[] = {-1, -1, -1, 0, 0, 1, 1, 1};
int T, n, m, k, fa[N], vis[N], Ans;
template <class T>
inline T Read(void) {
  bool w = 0;
  char c = ' ';
  T x = 0;
  while (!isdigit(c)) w |= c == '-', c = getchar();
  while (isdigit(c)) x = x * 10 + c - 48, c = getchar();
  return w ? -x : x;
}
inline int id(int x, int y) { return (x - 1) * 2 * m + y; }
inline int Find(int x) { return fa[x] == x ? x : fa[x] = Find(fa[x]); }
inline void Merge(int x, int y) {
  x = Find(x), y = Find(y);
  if (x ^ y) fa[x] = y;
}
inline bool Check(int &x, int &y) {
  if (!y) y = m << 1;
  if (y == (m << 1 | 1)) y = 1;
  return x >= 1 && x <= n && vis[id(x, y)];
}
inline bool Query(int x, int y) {
  int _x = x, _y = y + m;
  for (int i = 0; i < 8; i++) {
    int nx = x + dx[i], ny = y + dy[i];
    if (!Check(nx, ny)) continue;
    for (int j = 0; j < 8; j++) {
      int _nx = _x + dx[j], _ny = _y + dy[j];
      if (!Check(_nx, _ny)) continue;
      if (Find(id(nx, ny)) == Find(id(_nx, _ny))) return false;
    }
  }
  return true;
}
inline void Remove(int x, int y) {
  int _x = x, _y = y + m;
  for (int i = 0; i < 8; i++) {
    int nx = x + dx[i], ny = y + dy[i];
    if (Check(nx, ny)) Merge(id(x, y), id(nx, ny));
    int _nx = _x + dx[i], _ny = _y + dy[i];
    if (Check(_nx, _ny)) Merge(id(_x, _y), id(_nx, _ny));
  }
  vis[id(x, y)] = vis[id(_x, _y)] = 1;
}
int main(void) {
  T = 1;
  while (T-- > 0) {
    n = Read<int>(), m = Read<int>(), k = Read<int>(), Ans = 0;
    for (int i = 1; i <= n; i++)
      for (int j = 1; j <= m << 1; j++)
        fa[id(i, j)] = id(i, j), vis[id(i, j)] = 0;
    for (int i = 1; i <= k; i++) {
      int x = Read<int>(), y = Read<int>();
      if (m == 1) continue;
      if (Query(x, y)) Remove(x, y), ++Ans;
    }
    printf("%d\n", Ans);
  }
}
