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 = 3005;
int r, c, n, ans = 0;
int d[8][2] = {{1, 0},  {1, 1},   {0, 1},  {-1, 1},
               {-1, 0}, {-1, -1}, {0, -1}, {1, -1}};
int fa[maxn * maxn * 2];
bool note[maxn][maxn];
inline int id(int x, int y) { return (x - 1) * (2 * c) + y; }
bool exist(int &x, int &y) {
  if (!y)
    y = c << 1;
  else if (y == (c << 1 | 1))
    y = 1;
  return (x > 0 && x <= r && note[x][y]);
}
inline int find(int x) { return x == fa[x] ? x : fa[x] = find(fa[x]); }
inline void merge(int x, int y) {
  int xx = find(x), yy = find(y);
  fa[xx] = yy;
}
bool ok(int x, int y) {
  int xx = x, yy = y + c;
  for (int i = 0; i < 8; i++) {
    int dx = x + d[i][0], dy = y + d[i][1];
    if (!exist(dx, dy)) continue;
    for (int j = 0; j < 8; j++) {
      int dxx = xx + d[j][0], dyy = yy + d[j][1];
      if (!exist(dxx, dyy)) continue;
      if (find(id(dx, dy)) == find(id(dxx, dyy))) return false;
    }
  }
  return true;
}
void del(int x, int y) {
  int xx = x, yy = y + c;
  for (int i = 0; i < 8; i++) {
    int dx = x + d[i][0], dy = y + d[i][1];
    if (exist(dx, dy)) merge(id(x, y), id(dx, dy));
    dx = xx + d[i][0], dy = yy + d[i][1];
    if (exist(dx, dy)) merge(id(xx, yy), id(dx, dy));
  }
  note[xx][yy] = note[x][y] = true;
}
int main() {
  scanf("%d%d%d", &r, &c, &n);
  if (c <= 1) {
    printf("0");
    return 0;
  }
  for (int i = 1; i <= r; i++) {
    for (int j = 1; j <= c; j++) {
      fa[id(i, j + c)] = id(i, j + c);
      fa[id(i, j)] = id(i, j);
    }
  }
  int x, y;
  while (n--) {
    scanf("%d%d", &x, &y);
    if (ok(x, y)) {
      ans++;
      del(x, y);
    }
  }
  printf("%d", ans);
  return 0;
}
