#include <bits/stdc++.h>
using namespace std;
inline int read() {
  int x = 0;
  char c = getchar();
  while (!isdigit(c)) c = getchar();
  while (isdigit(c)) x = x * 10 + c - '0', c = getchar();
  return x;
}
const int maxn = 3000 * 6000 + 100;
int r, c, n, f[maxn], ans;
const int dx[] = {1, 0, -1, 0, 1, 1, -1, -1};
const int dy[] = {0, 1, 0, -1, 1, -1, 1, -1};
bool vis[3005][6005];
inline bool check(int &x, int &y) {
  if (y == 0)
    y = c * 2;
  else if (y == c * 2 + 1)
    y = 1;
  return (x > 0 && x <= r && vis[x][y]);
}
inline int find(int x) {
  if (f[x] == x) return x;
  return f[x] = find(f[x]);
}
bool chk(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 (!check(nx, ny)) continue;
    for (int j = 0; j < 8; j++) {
      int nx1 = x1 + dx[j], ny1 = y1 + dy[j];
      if (!check(nx1, ny1)) continue;
      if (find(((nx)-1) * 2 * c + (ny)) == find(((nx1)-1) * 2 * c + (ny1)))
        return false;
    }
  }
  return true;
}
inline void merge(int a, int b) { f[find(a)] = find(b); }
inline 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 (check(nx, ny)) merge(((x)-1) * 2 * c + (y), ((nx)-1) * 2 * c + (ny));
    int nx1 = x1 + dx[i], ny1 = y1 + dy[i];
    if (check(nx1, ny1))
      merge(((x1)-1) * 2 * c + (y1), ((nx1)-1) * 2 * c + (ny1));
  }
  vis[x][y] = 1;
  vis[x1][y1] = 1;
}
int main() {
  r = read(), c = read(), n = read();
  if (c == 1) printf("0"), exit(0);
  for (int i = 1; i <= r; i++)
    for (int j = 1; j <= c * 2; j++)
      f[((i)-1) * 2 * c + (j)] = ((i)-1) * 2 * c + (j);
  while (n--) {
    int x = read(), y = read();
    if (chk(x, y)) del(x, y), ans++;
  }
  printf("%d", ans);
  return 0;
}
