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 namespace std;
const int maxn = 18000000 + 5;
int r, c, m;
int s, t;
int f[maxn];
bool vis[maxn];
void init() {
  scanf("%d%d%d", &r, &c, &m);
  s = 0;
  t = 2 * r * c + 1;
  for (int i = 0; i <= t; ++i) f[i] = i;
}
int encode(int x, int y) {
  if (x < 1 || x > r) return -1;
  if (y == 0) return s;
  if (y == c * 2 + 1) return t;
  return (x - 1) * c * 2 + y;
}
int find(int x) {
  if (f[x] == x) return x;
  return f[x] = find(f[x]);
}
void merge(int x, int y) {
  x = find(x);
  y = find(y);
  if (x == y) return;
  f[x] = y;
}
int solve(int x, int y) {
  if (c == 1) return 0;
  int p;
  bool flag = false;
  set<int> left, right;
  set<int>::iterator it;
  vis[s] = vis[t] = true;
  for (int i = -1; i <= 1; ++i)
    for (int j = -1; j <= 1; ++j) {
      if (i == 0 && j == 0) continue;
      p = encode(x + i, y + j);
      if (p < 0 || !vis[p]) continue;
      left.insert(find(p));
    }
  for (int i = -1; i <= 1; ++i)
    for (int j = -1; j <= 1; ++j) {
      if (i == 0 && j == 0) continue;
      p = encode(x + i, y + c + j);
      if (p < 0 || !vis[p]) continue;
      right.insert(find(p));
    }
  if (left.count(find(s)) && left.count(find(t))) return 0;
  if (right.count(find(s)) && right.count(find(t))) return 0;
  for (it = left.begin(); it != left.end(); ++it) {
    if (*it == find(s)) continue;
    if (*it == find(p)) continue;
    if (right.count(*it)) {
      if (left.count(find(s)) && right.count(find(t))) return 0;
      if (left.count(find(t)) && right.count(find(s))) return 0;
    }
  }
  p = encode(x, y);
  vis[p] = true;
  for (it = left.begin(); it != left.end(); ++it) merge(p, *it);
  p = encode(x, y + c);
  vis[p] = true;
  for (it = right.begin(); it != right.end(); ++it) merge(p, *it);
  return 1;
}
int main() {
  init();
  int res = 0;
  while (m--) {
    int x, y;
    scanf("%d%d", &x, &y);
    res += solve(x, y);
  }
  printf("%d\n", res);
  return 0;
}
