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 dx[8] = {0, 0, -1, -1, -1, 1, 1, 1};
const int dy[8] = {-1, 1, -1, 0, 1, -1, 0, 1};
int r, c, n, res, a, b, f[18000005];
bool vis[3001][6001], g[3001][6001];
stack<pair<int, int> > stk;
void init() {
  for (int i = 0; i < r * c; ++i) f[i] = i;
}
int F(int x) {
  if (f[x] == x) return x;
  stk.push(pair<int, int>(x, f[x]));
  return f[x] = F(f[x]);
}
void U(int a, int b) {
  int fa = F(a), fb = F(b);
  stk.push(pair<int, int>(fa, f[fa]));
  f[fa] = fb;
}
int main() {
  scanf("%d%d%d", &r, &c, &n);
  c <<= 1;
  init();
  for (int i = 0; i < n; ++i) {
    scanf("%d%d", &a, &b);
    --a;
    --b;
    while (!stk.empty()) stk.pop();
    vis[a][b] = vis[a][b + c / 2] = true;
    for (int i = 0; i < 8; ++i) {
      int tx = a + dx[i], ty = b + dy[i];
      if (ty == -1) ty = c - 1;
      if (ty == c) ty = 0;
      if (tx < 0 || tx >= r || !vis[tx][ty]) continue;
      U(tx * c + ty, a * c + b);
    }
    b += c / 2;
    for (int i = 0; i < 8; ++i) {
      int tx = a + dx[i], ty = b + dy[i];
      if (ty == -1) ty = c - 1;
      if (ty == c) ty = 0;
      if (tx < 0 || tx >= r || !vis[tx][ty]) continue;
      U(tx * c + ty, a * c + b);
    }
    b -= c / 2;
    if (F(a * c + b) == F(a * c + b + c / 2)) {
      vis[a][b] = vis[a][b + c / 2] = false;
      while (!stk.empty()) {
        f[stk.top().first] = stk.top().second;
        stk.pop();
      }
    } else {
      vis[a][b] = vis[a][b + c / 2] = true;
      ++res;
    }
  }
  printf("%d\n", res);
  return 0;
}
