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 Read() {
  int i = 0, f = 1;
  char ch = 0;
  while (!isdigit(ch) && ch != '-') ch = getchar();
  if (ch == '-') ch = getchar(), f = -1;
  while (isdigit(ch)) i = (i << 1) + (i << 3) + ch - 48, ch = getchar();
  return i * f;
}
const int N = 2e7 + 5;
const int M = 3e3 + 5;
int r, c, n, fa[N], ans;
const int dx[8] = {1, 1, 0, -1, -1, -1, 0, 1};
const int dy[8] = {0, 1, 1, 1, 0, -1, -1, -1};
bool delt[M][M << 1];
int id(int x, int y) { return (x - 1) * c * 2 + y; }
int get(int x) { return x == fa[x] ? x : fa[x] = get(fa[x]); }
bool ok(int x, int y) {
  if (y == 0)
    y = c + c;
  else if (y == c + c + 1)
    y = 1;
  return (x > 0 && x <= r && delt[x][y]);
}
bool check(int x, int y) {
  int x1 = x, y1 = y + c;
  for (int i = 0; i < 8; ++i) {
    int nx = x + dx[i], ny = y + dy[i];
    if (!ok(nx, ny)) continue;
    for (int j = 0; j < 8; ++j) {
      int nx1 = x1 + dx[j], ny1 = y1 + dy[j];
      if (!ok(nx1, ny1)) continue;
      if (get(id(nx, ny)) == get(id(nx1, ny1))) return false;
    }
  }
  return true;
}
void del(int x, int y) {
  int x1 = x, y1 = y + c;
  for (int i = 0; i < 8; ++i) {
    int nx = x + dx[i], ny = y + dy[i];
    if (ok(nx, ny)) fa[get(id(x, y))] = get(id(nx, ny));
    nx = x1 + dx[i], ny = y1 + dy[i];
    if (ok(nx, ny)) fa[get(id(x1, y1))] = get(id(nx, ny));
  }
  delt[x][y] = true;
  delt[x1][y1] = true;
}
int main() {
  r = Read(), c = Read(), n = Read();
  if (c == 1) {
    puts("0");
    return 0;
  }
  for (int i = 1; i <= r; ++i)
    for (int j = 1; j <= c * 2; ++j) fa[id(i, j)] = id(i, j);
  for (int i = 1; i <= n; ++i) {
    int x = Read(), y = Read();
    if (check(x, y)) del(x, y), ++ans;
  }
  printf("%d\n", ans);
  return 0;
}
