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 M = 3005;
int r, c, cc, n;
int fa[M * M * 3];
int getfa(int x) {
  if (fa[x] == x) return x;
  return fa[x] = getfa(fa[x]);
}
int ans;
int getid(int x, int y) { return x * cc + y; }
int rx[] = {1, 1, 1, 0, 0, -1, -1, -1};
int ry[] = {1, 0, -1, 1, -1, 1, 0, -1};
int mark[M][M * 2];
int main() {
  scanf("%d %d %d", &r, &c, &n);
  cc = c + c;
  if (c == 1) {
    puts("0");
    return 0;
  }
  for (int i = 1, x, y, xx, yy, nx, ny, f, id1, id2, ida, idb; i <= n; i++) {
    scanf("%d %d", &x, &y);
    xx = x, yy = y + c;
    ida = getid(x, y), idb = getid(xx, yy);
    f = true;
    for (int j = 0; j < 8; j++) {
      nx = x + rx[j], ny = y + ry[j];
      if (ny < 1) ny = cc;
      if (ny > cc) ny = 1;
      if (mark[nx][ny] == 0) continue;
      id1 = getid(nx, ny);
      id1 = getfa(id1);
      for (int k = 0; k < 8; k++) {
        nx = xx + rx[k], ny = yy + ry[k];
        if (ny < 1) ny = cc;
        if (ny > cc) ny = 1;
        if (mark[nx][ny] == 0) continue;
        id2 = getid(nx, ny);
        id2 = getfa(id2);
        if (id1 == id2) f = false;
      }
    }
    if (f) {
      ans++;
      fa[ida] = ida;
      for (int j = 0; j < 8; j++) {
        nx = x + rx[j], ny = y + ry[j];
        if (ny < 1) ny = cc;
        if (ny > cc) ny = 1;
        if (mark[nx][ny] == 0) continue;
        id1 = getid(nx, ny);
        id1 = getfa(id1);
        fa[id1] = ida;
      }
      fa[idb] = idb;
      for (int k = 0; k < 8; k++) {
        nx = xx + rx[k], ny = yy + ry[k];
        if (ny < 1) ny = cc;
        if (ny > cc) ny = 1;
        if (mark[nx][ny] == 0) continue;
        id2 = getid(nx, ny);
        id2 = getfa(id2);
        fa[id2] = idb;
      }
      mark[x][y] = mark[xx][yy] = 1;
    }
  }
  printf("%d\n", ans);
  return 0;
}
