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>
int fa[18000100], num[3010][6010], top;
int clo[18000100], tim;
bool color[3010][6010];
int mx[10] = {-1, -1, -1, 0, 0, 1, 1, 1}, my[10] = {-1, 0, 1, -1, 1, -1, 0, 1};
int r, c, n, ans;
int find(int x) {
  if (x == fa[x]) return x;
  return fa[x] = find(fa[x]);
}
inline bool check(int x, int y) {
  int i, xx, yy;
  ++tim;
  for (i = 0; i < 8; ++i) {
    xx = x + mx[i];
    yy = y + my[i];
    if (yy == 0) yy = 2 * c;
    if (color[xx][yy] && num[xx][yy]) clo[find(num[xx][yy])] = tim;
  }
  y += c;
  for (i = 0; i < 8; ++i) {
    xx = x + mx[i];
    yy = y + my[i];
    if (yy == 2 * c + 1) yy = 1;
    if (color[xx][yy] && num[xx][yy] && clo[find(num[xx][yy])] == tim) return 0;
  }
  return 1;
}
void add(int x, int y) {
  int i, xx, yy;
  for (i = 0; i < 8; ++i) {
    xx = x + mx[i];
    yy = y + my[i];
    if (yy == 2 * c + 1) yy = 1;
    if (yy == 0) yy = 2 * c;
    if (num[xx][yy] && color[xx][yy]) fa[find(num[xx][yy])] = num[x][y];
  }
}
int main() {
  int i, j, k, x, y;
  scanf("%d%d%d", &r, &c, &n);
  if (c == 1) {
    puts("0");
    return 0;
  }
  for (i = 1; i <= r; ++i)
    for (j = 1; j <= c * 2; ++j) {
      num[i][j] = ++top;
      fa[top] = top;
    }
  for (i = 1; i <= n; ++i) {
    scanf("%d%d", &x, &y);
    if (!check(x, y)) continue;
    ++ans;
    color[x][y] = color[x][y + c] = 1;
    add(x, y);
    add(x, y + c);
  }
  printf("%d\n", ans);
  return 0;
}
