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 maxn = 3000 + 10, xx[] = {-1, -1, -1, 0, 1, 1, 1, 0},
          yy[] = {-1, 0, 1, 1, 1, 0, -1, -1};
int r, c, n, id[maxn][maxn * 2], fa[maxn * maxn * 2], ans;
bool vis[maxn][maxn * 2];
int find(int u) {
  if (fa[u] != u) fa[u] = find(fa[u]);
  return fa[u];
}
void solve(int u, int v) {
  int Na = 0, a[20], Nb = 0, b[20];
  for (int i = 0; i < 8; i++) {
    int u1 = u + xx[i], v1 = v + yy[i];
    if (!v1) v1 = 2 * c;
    if (v1 > 2 * c) v1 = 1;
    if (vis[u1][v1]) a[Na++] = find(id[u1][v1]);
  }
  for (int i = 0; i < 8; i++) {
    int u1 = u + xx[i], v1 = v + c + yy[i];
    if (!v1) v1 = 2 * c;
    if (v1 > 2 * c) v1 = 1;
    if (vis[u1][v1]) b[Nb++] = find(id[u1][v1]);
  }
  for (int i = 0; i < Na; i++)
    for (int j = 0; j < Nb; j++)
      if (a[i] == b[j]) return;
  ans++;
  vis[u][v] = vis[u][v + c] = 1;
  for (int i = 0; i < Na; i++) fa[a[i]] = id[u][v];
  for (int i = 0; i < Nb; i++) fa[b[i]] = id[u][v + c];
}
int main() {
  cin >> r >> c >> n;
  int cnt = 0;
  for (int i = 1; i <= r; i++)
    for (int j = 1; j <= 2 * c; j++) {
      cnt++;
      id[i][j] = cnt;
      fa[cnt] = cnt;
    }
  while (n--) {
    int u, v;
    scanf("%d%d", &u, &v);
    solve(u, v);
  }
  if (c == 1) ans = 0;
  cout << ans;
  return 0;
}
