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 = 18000500;
int R, C, n;
int fa[maxn];
bool vis[5005][7005];
int fuck[maxn];
int nx[] = {0, 0, 1, -1, 1, -1, 1, -1};
int ny[] = {1, -1, 0, 0, 1, -1, -1, 1};
inline int get(int r, int c) { return (r - 1) * 2 * C + c; }
inline int getfa(int x) { return fa[x] == x ? x : fa[x] = getfa(fa[x]); }
inline bool OK(int r, int c) {
  if (r >= 1 && r <= R && c >= 1 && c <= 2 * C) return 1;
  return 0;
}
int main() {
  for (register int i = 0; i < maxn; i++) fa[i] = i;
  scanf("%d%d%d", &R, &C, &n);
  int ans = 0;
  for (register int t = 1, r, c; t <= n; t++) {
    scanf("%d%d", &r, &c);
    bool flag = 0;
    int c1 = c + C;
    for (register int i = 0; i < 8; i++) {
      int nr = r + nx[i], nc = c + ny[i];
      if (nc == 0) nc = 2 * C;
      if (!OK(nr, nc) || !vis[nr][nc]) continue;
      fuck[getfa(get(nr, nc))] = t;
    }
    for (register int i = 0; i < 8; i++) {
      if (flag) break;
      int nr = r + nx[i], nc = c + ny[i] + C;
      if (nc == 2 * C + 1) nc = 1;
      if (!OK(nr, nc) || !vis[nr][nc]) continue;
      if (fuck[getfa(get(nr, nc))] == t) {
        flag = 1;
      }
    }
    if (!flag) {
      ans++;
      vis[r][c] = vis[r][c1] = 1;
      for (register int i = 0; i < 8; i++) {
        int nr = r + nx[i], nc = c + ny[i], ncc = nc + C;
        if (nc == 0) nc = 2 * C;
        if (ncc == 2 * C + 1) ncc = 1;
        if (!OK(nr, nc) || !vis[nr][nc]) continue;
        fa[getfa(get(nr, nc))] = getfa(get(r, c));
        fa[getfa(get(nr, ncc))] = getfa(get(r, c + C));
      }
    }
  }
  if (C == 1) {
    cout << 0 << endl;
    return 0;
  }
  cout << ans << endl;
}
