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>
const int MAXN = 9001000;
int N;
int R, C;
int conv(int x, int y) {
  if (y <= 0) return -1;
  if (y > C) return -1;
  if (x == 0) return 1;
  if (x == R + 1) return 2;
  return C * x + y + 10;
}
bool vis[MAXN];
int par[MAXN];
int find(int x) {
  if (par[x] == x) return x;
  return par[x] = find(par[x]);
}
void join(int a, int b) {
  a = find(a);
  b = find(b);
  par[a] = b;
}
int main() {
  scanf("%d %d %d", &R, &C, &N);
  for (int i = 1; i <= R; ++i) {
    for (int j = 1; j <= C; ++j) {
      int x = conv(i, j);
      par[x] = x;
    }
  }
  par[1] = 1;
  par[2] = 2;
  vis[1] = true;
  vis[2] = true;
  int cnt = 0;
  for (int i = 0; i < N; ++i) {
    int a, b;
    scanf("%d %d", &a, &b);
    bool left = false;
    bool right = false;
    for (int x = a - 1; x <= a + 1; ++x) {
      for (int y = b - 1; y <= b + 1; ++y) {
        int k = conv(x, y);
        if (k != -1 && vis[k]) {
          if (find(k) == find(1)) left = true;
          if (find(k) == find(2)) right = true;
        }
      }
    }
    if (!left || !right) {
      ++cnt;
      int p = conv(a, b);
      vis[p] = true;
      for (int x = a - 1; x <= a + 1; ++x) {
        for (int y = b - 1; y <= b + 1; ++y) {
          int q = conv(x, y);
          if (vis[q]) join(p, q);
        }
      }
    }
  }
  printf("%d\n", cnt);
  return 0;
}
