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 wayx[8] = {-1, -1, -1, 0, 0, 1, 1, 1};
const int wayy[8] = {1, -1, 0, 1, -1, 1, -1, 0};
int id[3100][6100], fa[5100000];
int st[11000000], sf[11000000], top, num;
int n, m, k, ans;
int find(int x) {
  if (fa[x] == x) return x;
  st[++top] = x;
  sf[top] = fa[x];
  fa[x] = find(fa[x]);
  return fa[x];
}
void Union(int x, int y) {
  if (!x || !y || x == y) return;
  x = find(x), y = find(y);
  st[++top] = x;
  sf[top] = x;
  fa[x] = y;
}
void clear() {
  for (; top; top--) fa[st[top]] = sf[top];
}
int main() {
  scanf("%d %d %d", &n, &m, &k);
  for (int i = 1; i <= k + k; i++) fa[i] = i;
  while (k--) {
    int x, y;
    scanf("%d %d", &x, &y);
    id[x][y] = ++num;
    id[x][y + m] = ++num;
    if (y == m) id[x][0] = num;
    if (y == 1) id[x][m + m + 1] = num - 1;
    top = 0;
    int now = id[x][y];
    for (int i = 0; i < 8; i++) Union(now, id[x + wayx[i]][y + wayy[i]]);
    y += m;
    now = id[x][y];
    for (int i = 0; i < 8; i++) Union(now, id[x + wayx[i]][y + wayy[i]]);
    if (find(num - 1) == find(num)) {
      clear();
      id[x][y] = id[x][y - m] = 0;
      if (y == m + m) id[x][0] = 0;
      if (y == m + 1) id[x][m + m + 1] = 0;
      continue;
    }
    ans++;
  }
  printf("%d\n", ans);
  return 0;
}
