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 BufferSize = 1 << 16;
char buffer[BufferSize], *Head, *Tail;
inline char Getchar() {
  if (Head == Tail) {
    int l = fread(buffer, 1, BufferSize, stdin);
    Tail = (Head = buffer) + l;
  }
  return *Head++;
}
int read() {
  int x = 0, f = 1;
  char c = Getchar();
  while (!isdigit(c)) {
    if (c == '-') f = -1;
    c = Getchar();
  }
  while (isdigit(c)) {
    x = x * 10 + c - '0';
    c = Getchar();
  }
  return x * f;
}
int r, c, n;
bool has[3005][3005 << 1];
int fa[18000010];
int findset(int x) { return x == fa[x] ? x : fa[x] = findset(fa[x]); }
int dx[8] = {-1, 1, 0, 0, -1, 1, 1, -1}, dy[8] = {0, 0, -1, 1, -1, 1, -1, 1};
int idx(int x, int y) { return x * c + y; }
int main() {
  r = read();
  c = (read() << 1);
  n = read();
  int c2 = c >> 1;
  for (int i = 0; i <= r * c + 1; i++) fa[i] = i;
  int s = r * c, t = s + 1;
  for (int i = 0; i < r; i++) {
    int u = findset(idx(i, 0)), v = findset(s);
    if (u != v) fa[v] = u;
    u = findset(idx(i, c - 1));
    v = findset(t);
    if (u != v) fa[v] = u;
  }
  int ans = 0;
  for (int kase = 1; kase <= n; kase++) {
    int x = read() - 1, y = read() - 1, a = idx(x, y);
    int x2 = x, y2 = y + c2, b = idx(x2, y2);
    has[x][y] = has[x2][y2] = 1;
    int at[10], bt[10], cat = 0, cbt = 0;
    for (int i = 0; i < 8; i++) {
      int tx = x + dx[i], ty = y + dy[i];
      if (0 <= tx && tx < r && 0 <= ty && ty < c && has[tx][ty])
        at[++cat] = idx(tx, ty);
    }
    for (int i = 0; i < 8; i++) {
      int tx = x2 + dx[i], ty = y2 + dy[i];
      if (0 <= tx && tx < r && 0 <= ty && ty < c && has[tx][ty])
        bt[++cbt] = idx(tx, ty);
    }
    bool S = 0, T = 0, con = 0;
    for (int i = 1; i <= cat; i++)
      if (findset(at[i]) == findset(s)) {
        S = 1;
        break;
      }
    if (findset(a) == findset(s)) S = 1;
    for (int i = 1; i <= cbt; i++)
      if (findset(bt[i]) == findset(t)) {
        T = 1;
        break;
      }
    if (findset(b) == findset(t)) T = 1;
    for (int i = 1; i <= cat; i++) {
      for (int j = 1; j <= cbt; j++)
        if (findset(at[i]) == findset(bt[j])) {
          con = 1;
          break;
        }
      if (con) break;
    }
    if (S && T && con)
      has[x][y] = has[x2][y2] = 0;
    else {
      ans++;
      for (int i = 1; i <= cat; i++) {
        int u = findset(at[i]), v = findset(a);
        if (u != v) fa[v] = u;
      }
      for (int i = 1; i <= cbt; i++) {
        int u = findset(bt[i]), v = findset(b);
        if (u != v) fa[v] = u;
      }
    }
  }
  printf("%d\n", ans);
  return 0;
}
