2 5 10
2 2
1 1
1 4
2 1
1 2
1 5
2 4
2 5
1 3
2 3
 2 2 2
1 1
2 2
 3 3 9
1 1
1 2
1 3
2 1
2 2
2 3
3 1
3 2
3 3
 7 5 35
5 3
3 5
1 1
2 5
6 4
7 2
5 1
3 4
6 5
7 3
4 1
2 2
4 2
2 4
4 3
3 3
6 1
1 2
4 5
1 3
2 1
5 5
7 5
7 1
6 2
1 4
1 5
3 2
4 4
5 2
2 3
6 3
7 4
5 4
3 1
 1 5 4
1 1
1 2
1 4
1 5
 1 1 1
1 1
 5 7 21
4 4
4 5
5 5
5 6
5 7
5 1
5 2
4 2
3 2
3 1
3 7
3 6
2 6
1 6
1 7
1 1
1 2
1 3
1 4
2 4
3 4
 2 1 1
1 1
 2 2 4
2 1
1 1
1 2
2 2
 3000 3000 1
2222 738
 5 7 35
1 2
2 3
5 1
5 7
4 4
5 3
3 1
2 6
4 5
2 7
4 1
2 1
2 2
1 7
5 6
3 6
4 6
1 6
1 1
3 3
3 4
4 2
2 5
5 5
3 5
2 4
1 5
1 3
4 3
5 4
1 4
3 7
4 7
3 2
5 2
 5 4 1
4 1
 3 4 12
2 3
3 2
2 2
2 1
1 2
3 1
1 4
1 3
3 3
2 4
3 4
1 1
 3 3 3
1 1
2 2
3 3

8
 1
 6
 26
 4
 0
 20
 0
 2
 1
 28
 1
 9
 3

#include <bits/stdc++.h>
using std::make_pair;
using std::map;
using std::pair;
using std::queue;
map<pair<int, int>, int> mp;
const int MAXN = 4e6 + 7;
int r, c, m, T, x, y;
int fa[MAXN];
int pos[6010][3050];
const int dx[9] = {0, 1, 1, 1, 0, 0, -1, -1, -1};
const int dy[9] = {0, 1, 0, -1, 1, -1, 1, 0, -1};
struct tmpc {
  int x, y, t;
  tmpc() : x(0), y(0), t(0) {}
  tmpc(int x, int y, int z) : x(x), y(y), t(z) {}
};
queue<tmpc> que;
inline int getf(int x) { return x == fa[x] ? x : fa[x] = getf(fa[x]); }
inline void merge(int x, int y) {
  fa[getf(x)] = getf(y);
  return;
}
inline int cnw(int x, int y) {
  if (mp.find(make_pair(x, y)) != mp.end()) return mp[make_pair(x, y)];
  mp[make_pair(x, y)] = ++T, fa[T] = T;
  return T;
}
inline void back_rc(int x, int y) {
  for (int i = 0; i <= 8; i++) {
    que.push(
        tmpc((dx[i] + x), (dy[i] + y), getf(cnw((dx[i] + x), (dy[i] + y)))));
    que.push(tmpc((dx[i] + x), (dy[i] + y) + c,
                  getf(cnw((dx[i] + x), (dy[i] + y) + c))));
  }
  return;
}
inline void back_real() {
  while (!que.empty()) {
    tmpc q = que.front();
    que.pop();
    fa[cnw(q.x, q.y)] = q.t;
  }
  return;
}
inline void back_fake() {
  while (!que.empty()) que.pop();
}
inline int back_check(int x, int y) {
  for (int i = 1; i <= 8; i++) {
    if (pos[(dx[i] + x)][(dy[i] + y)] &&
        getf(cnw((dx[i] + x), (dy[i] + y))) ==
            getf(cnw((dx[i] + x), (dy[i] + y) + c))) {
      return 1;
    }
  }
  return 0;
}
int main() {
  scanf("%d%d%d", &r, &c, &m);
  int cnt = 0;
  for (int i = 1, x, y; i <= m; i++) {
    scanf("%d%d", &x, &y);
    bool flag = 1;
    back_rc(x, y);
    for (int i = 1; i <= 8; i++) {
      if (pos[dx[i] + x][dy[i] + y])
        merge(cnw(x, y), cnw(dx[i] + x, dy[i] + y));
      if (pos[dx[i] + x][dy[i] + y + c])
        merge(cnw(x, y + c), cnw(dx[i] + x, dy[i] + y + c));
    }
    if (back_check(x, y)) {
      back_real();
      continue;
    }
    pos[x][y] = pos[x][y + c] = 1;
    cnt++;
    back_fake();
  }
  printf("%d\n", cnt);
  return 0;
}
