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, ans;
int top, st[25][2];
int vis[3005][6005];
int fa[18000005], siz[18000005];
int gox[8] = {0, 0, 1, 1, 1, -1, -1, -1}, goy[8] = {1, -1, 0, 1, -1, 0, 1, -1};
int getid(int x, int y) { return (x - 1) * c * 2 + y; }
int getfather(int x) {
  if (fa[x] == x) return x;
  return getfather(fa[x]);
}
void link(int x, int y) {
  x = getfather(x);
  y = getfather(y);
  if (x == y) return;
  if (siz[x] > siz[y]) swap(x, y);
  fa[x] = y;
  siz[y] += siz[x];
  ++top;
  st[top][0] = x;
  st[top][1] = y;
  return;
}
void cut(int x, int y) {
  fa[x] = x;
  siz[y] -= siz[x];
  return;
}
int main() {
  scanf("%d%d%d", &r, &c, &n);
  if (c == 1) {
    printf("0");
    return 0;
  }
  for (int i = 1; i <= 2 * r * c; ++i) {
    fa[i] = i;
    siz[i] = 1;
  }
  for (int i = 1; i <= n; ++i) {
    int x, y;
    scanf("%d%d", &x, &y);
    for (int j = 0; j < 8; ++j) {
      int xx, yy;
      xx = x + gox[j];
      yy = y + goy[j];
      if (yy == 0) yy = 2 * c;
      if (yy == 2 * c + 1) yy = 1;
      if (xx >= 1 && xx <= r && yy >= 1 && yy <= 2 * c && vis[xx][yy])
        link(getid(x, y), getid(xx, yy));
      xx = x + gox[j];
      yy = y + c + goy[j];
      if (yy == 0) yy = 2 * c;
      if (yy == 2 * c + 1) yy = 1;
      if (xx >= 1 && xx <= r && yy >= 1 && yy <= 2 * c && vis[xx][yy])
        link(getid(x, y + c), getid(xx, yy));
    }
    if (getfather(getid(x, y)) == getfather(getid(x, y + c)))
      while (top) {
        cut(st[top][0], st[top][1]);
        --top;
      }
    else {
      vis[x][y] = 1;
      vis[x][y + c] = 1;
      top = 0;
      ++ans;
    }
  }
  printf("%d", ans);
  return 0;
}
