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;
int fa[4005 * 4005 * 2];
int mark[4005 * 4005 * 2], tim;
bool mp[4005 * 4005 * 2];
int n, r, c, ans;
int dx[9] = {-1, -1, -1, 0, 1, 1, 1, 0, 0};
int dy[9] = {-1, 0, 1, 1, 1, 0, -1, -1, 0};
int find(int x) { return fa[x] == x ? x : fa[x] = find(fa[x]); }
bool work(int &x, int &y) {
  if (x < 1 || x > r) return 0;
  if (y == 0) y = 2 * c;
  if (y == 2 * c + 1) y = 1;
  return 1;
}
int main() {
  cin >> r >> c >> n;
  for (int i = 1; i <= r * c * 2; i++) fa[i] = i;
  for (int x, y, k = 1; k <= n; k++) {
    scanf("%d%d", &x, &y);
    tim++;
    if (mp[((x - 1) * c * 2 + y)]) {
      ans++;
      continue;
    }
    mp[((x - 1) * c * 2 + y)] = mp[((x - 1) * c * 2 + y + c)] = 1;
    for (int tx, ty, i = 0; i < 9; i++) {
      tx = x + dx[i];
      ty = y + dy[i];
      if (work(tx, ty) && mp[((tx - 1) * c * 2 + ty)])
        mark[find(((tx - 1) * c * 2 + ty))] = tim;
    }
    bool flag = 1;
    for (int tx, ty, i = 0; i < 8; i++) {
      tx = x + dx[i];
      ty = y + dy[i] + c;
      if (work(tx, ty) && mp[((tx - 1) * c * 2 + ty)] &&
          mark[find(((tx - 1) * c * 2 + ty))] == tim) {
        flag = 0;
        break;
      }
    }
    if (flag) {
      ans++;
      for (int tx, ty, i = 0; i < 8; i++) {
        tx = x + dx[i];
        ty = y + dy[i];
        if (work(tx, ty) && mp[((tx - 1) * c * 2 + ty)])
          fa[find(((tx - 1) * c * 2 + ty))] = ((x - 1) * c * 2 + y);
        tx = x + dx[i];
        ty = y + dy[i] + c;
        if (work(tx, ty) && mp[((tx - 1) * c * 2 + ty)])
          fa[find(((tx - 1) * c * 2 + ty))] = ((x - 1) * c * 2 + y + c);
      }
    } else
      mp[((x - 1) * c * 2 + y)] = mp[((x - 1) * c * 2 + y + c)] = 0;
  }
  cout << ans << endl;
}
