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 r, c, n, res, a, b, f[18000005], le[18000005], ri[18000005], ml, mr;
bool vis[3001][6001], flag;
void init() {
  for (int i = 0; i < r * c; ++i) {
    le[i] = ri[i] = i % c;
    f[i] = i;
  }
}
int F(int x) {
  if (f[x] == x) return x;
  int tx = F(f[x]);
  le[tx] = min(le[tx], le[x]);
  ri[tx] = max(ri[tx], ri[x]);
  return f[x] = tx;
}
void U(int a, int b) {
  int fa = F(a), fb = F(b);
  le[fb] = min(le[fb], le[fa]);
  ri[fb] = max(ri[fb], ri[fa]);
  f[fa] = fb;
}
int main() {
  freopen("in.txt", "r", stdin);
  scanf("%d%d%d", &r, &c, &n);
  c <<= 1;
  init();
  for (int i = 0; i < n; ++i) {
    scanf("%d%d", &a, &b);
    --a;
    --b;
    ml = c;
    mr = -1;
    flag = false;
    for (int j = -1; j <= 1; ++j)
      for (int k = -1; k <= 1; ++k) {
        if (j == 0 && k == 0) continue;
        int tx = a + j, ty = b + k;
        if (tx < 0 || tx >= r || ty < 0 || ty >= c || !vis[tx][ty]) continue;
        ml = min(ml, le[F(tx * c + ty)]);
        mr = max(mr, ri[F(tx * c + ty)]);
      }
    if (mr - ml + 1 >= c / 2) flag = true;
    ml = c;
    mr = -1;
    b += c / 2;
    for (int j = -1; j <= 1; ++j)
      for (int k = -1; k <= 1; ++k) {
        if (j == 0 && k == 0) continue;
        int tx = a + j, ty = b + k;
        if (tx < 0 || tx >= r || ty < 0 || ty >= c || !vis[tx][ty]) continue;
        ml = min(ml, le[F(tx * c + ty)]);
        mr = max(mr, ri[F(tx * c + ty)]);
      }
    if (mr - ml + 1 >= c / 2) flag = true;
    if (flag) continue;
    ++res;
    b -= c / 2;
    vis[a][b] = vis[a][b + c / 2] = true;
    for (int j = -1; j <= 1; ++j)
      for (int k = -1; k <= 1; ++k) {
        if (j == 0 && k == 0) continue;
        int tx = a + j, ty = b + k;
        if (tx > 0 && tx <= r && ty > 0 && ty <= c && vis[tx][ty])
          U(a * c + b, tx * c + ty);
        ty += c / 2;
        if (tx > 0 && tx <= r && ty > 0 && ty <= c && vis[tx][ty])
          U(a * c + b + c / 2, tx * c + ty);
      }
  }
  printf("%d\n", res);
  return 0;
}
