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 mod = int(1e9) + 7, INF = 0x3f3f3f3f;
const int maxn = 1e5 + 13;
int F[100000];
int r, c, n, x, y, ans;
int find(int x) {
  if (F[x] == -1)
    return x;
  else
    return F[x] = find(F[x]);
}
void bing(int x, int y) {
  int t1 = find(x);
  int t2 = find(y);
  if (t1 != t2) F[t1] = t2;
}
bool mp[6010][3010];
void letin(int x, int y) {
  if (mp[x - 1][y - 1] || mp[x - 1][y] || mp[x - 1][y + 1]) bing(x - 1, x);
  if (mp[x + 1][y - 1] || mp[x + 1][y] || mp[x + 1][y + 1]) bing(x + 1, x);
  if (mp[x - 1 + r][y - 1] || mp[x - 1 + r][y] || mp[x - 1 + r][y + 1])
    bing(x - 1 + r, x + r);
  if (mp[x + 1 + r][y - 1] || mp[x + 1 + r][y] || mp[x + 1 + r][y + 1])
    bing(x + 1 + r, x + r);
  mp[x][y] = mp[x + r][y] = true;
  ans++;
}
int main(void) {
  scanf("%d%d%d", &r, &c, &n);
  memset(F, -1, sizeof(F));
  bing(0, 1);
  bing(2 * r, 2 * r + 1);
  bing(2 * r + 1, 0);
  ans = 0;
  while (n--) {
    scanf("%d%d", &x, &y);
    bool f1 = find(x - 1) == find(x + r + 1);
    bool f2 = find(x + 1) == find(x + r - 1);
    if (f1 && f2) {
      bool f3 = find(x - 1) == find(x);
      if (!f3)
        if (mp[x - 1][y - 1] || mp[x - 1][y] || mp[x - 1][y + 1]) f3 = true;
      bool f4 = find(x) == find(x + 1);
      if (!f4)
        if (mp[x + 1][y - 1] || mp[x + 1][y] || mp[x + 1][y + 1]) f4 = true;
      bool f5 = find(x - 1 + r) == find(x + r);
      if (!f5)
        if (mp[x - 1 + r][y - 1] || mp[x - 1 + r][y] || mp[x - 1 + r][y + 1])
          f5 = true;
      bool f6 = find(x + 1 + r) == find(x + r);
      if (!f6)
        if (mp[x + 1 + r][y - 1] || mp[x + 1 + r][y] || mp[x + 1 + r][y + 1])
          f6 = true;
      if (f3 && f4 && f5 && f6)
        continue;
      else
        letin(x, y);
    } else {
      letin(x, y);
    }
  }
  printf("%d\n", ans);
  return 0;
}
