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 dx[8] = {0, 0, 1, 1, 1, -1, -1, -1};
int dy[8] = {1, -1, 1, 0, -1, 1, 0, -1};
int r, c, n;
int fa[18000010], siz[18000010];
int vis[3010][6010];
int ans;
vector<int> o;
inline int id(int x, int y) { return (x - 1) * c * 2 + y; }
inline int find(int x) {
  if (fa[x] == x) return x;
  return find(fa[x]);
}
void solve(int x, int y) {
  int idu = id(x, y);
  for (int w = 0; w < 8; w++) {
    int xx = x + dx[w], yy = y + dy[w];
    if (yy < 1)
      yy += c + c;
    else if (yy > c + c)
      yy -= c + c;
    if (xx < 1 || xx > r) continue;
    if (!vis[xx][yy]) continue;
    int idv = id(xx, yy);
    idu = find(idu), idv = find(idv);
    if (idu != idv) {
      if (siz[idu] < siz[idv])
        siz[idv] += siz[idu], fa[idu] = idv, o.push_back(idu);
      else
        siz[idu] += siz[idv], fa[idv] = idu, o.push_back(idv);
    }
  }
}
int main() {
  scanf("%d%d%d", &r, &c, &n);
  if (c == 1) return puts("0"), 0;
  for (int i = 1; i <= r; i++)
    for (int j = 1; j <= c + c; j++) fa[id(i, j)] = id(i, j), siz[id(i, j)] = 1;
  while (n--) {
    int x, y;
    scanf("%d%d", &x, &y);
    vis[x][y] = vis[x][y + c] = 1;
    o.clear();
    solve(x, y), solve(x, y + c);
    if (find(id(x, y)) == find(id(x, y + c))) {
      vis[x][y] = vis[x][y + c] = 0;
      for (int v : o) siz[fa[v]] -= siz[v], fa[v] = v;
    } else
      ans++;
  }
  printf("%d\n", ans);
}
