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 f[20000000], ans;
int a[8] = {-1, 0, 1, -1, 1, -1, 0, 1};
int b[8] = {-1, -1, -1, 0, 0, 1, 1, 1};
bool flag[3100][3100];
int r, c, n, tot, g1[10001], g2[10001];
int gf(int k) {
  g1[++tot] = k;
  g2[tot] = f[k];
  if (f[k] != k) f[k] = gf(f[k]);
  return f[k];
}
void un(int u, int v) {
  u = gf(u);
  v = gf(v);
  g1[++tot] = u;
  g2[tot] = f[u];
  f[u] = v;
}
void work(int x, int y) {
  for (int i = 0; i < 8; i++) {
    int tx = x + a[i], ty = y + b[i];
    if (ty == 0)
      ty = 2 * c;
    else if (ty > 2 * c)
      ty = 1;
    if (tx == 0 || tx > r) continue;
    int poi = (tx - 1) * 2 * c + ty;
    if (flag[tx][ty]) un((x - 1) * c * 2 + y, poi);
  }
}
int main() {
  scanf("%d%d%d", &r, &c, &n);
  for (int i = 1; i <= r * c * 2; i++) f[i] = i;
  while (n--) {
    int x, y;
    tot = 0;
    scanf("%d%d", &x, &y);
    int now = (x - 1) * 2 * c + y;
    flag[x][y] = flag[x][y + c] = 1;
    work(x, y);
    work(x, y + c);
    if (gf(now) == gf(now + c)) {
      flag[x][y] = flag[x][y + c] = 0;
      for (int i = tot; i; i--) f[g1[i]] = g2[i];
    } else {
      ans++;
    }
  }
  printf("%d\n", ans);
  return 0;
}
