#include <bits/stdc++.h>
using namespace std;
inline void read(long long& x) {
  static char c;
  register long long f = 1;
  while (!isdigit(c = getchar())) {
    if (c == '-') f = -1;
  }
  x = c & 15;
  while (isdigit(c = getchar())) {
    x *= 10;
    x += c & 15;
  }
  x *= f;
}
inline void read(int& x) {
  static char c;
  register int f = 1;
  while (!isdigit(c = getchar())) {
    if (c == '-') f = -1;
  }
  x = c & 15;
  while (isdigit(c = getchar())) {
    x *= 10;
    x += c & 15;
  }
  x *= f;
}
inline void write(long long x) {
  if (x < 0) putchar('-'), x = -x;
  if (x > 9) write(x / 10);
  putchar('0' | x % 10);
}
int r, c, n;
pair<int, int> st[3002][6002];
bool u[3002][6002];
pair<int, int> fa(const pair<int, int>& a) {
  if (st[a.first][a.second] == a) return a;
  return st[a.first][a.second] = fa(st[a.first][a.second]);
}
void ad(const pair<int, int>& a, const pair<int, int>& b) {
  st[fa(b).first][fa(b).second] = fa(a);
}
int cg1(const int& y) {
  if (y > c << 1) return y - (c << 1);
  if (y < 1) return y + (c << 1);
  return y;
}
int cg2(const int& y) {
  if (y > c << 1) return y - (c << 1);
  if (y < 1) return y + (c << 1);
  return y;
}
bool hf(const int& x) {
  if (x < 1 || x > r) return 0;
  return 1;
}
int dx[8] = {-1, 0, 1, -1, 1, -1, 0, 1}, dy[8] = {-1, -1, -1, 0, 0, 1, 1, 1};
int main() {
  read(r), read(c), read(n);
  int x, y;
  if (c == 1) {
    write(0);
    return 0;
  }
  int cnt = 0;
  for (int i = 1; i <= r; i++) {
    for (int j = 1; j <= c << 1; j++) {
      st[i][j] = pair<int, int>(i, j);
    }
  }
  for (int i = 1; i <= n; i++) {
    read(x), read(y);
    for (int i = 0; i < 8; i++) {
      for (int j = 0; j < 8; j++) {
        if (hf(x + dx[i]) && hf(x + dx[j]) && u[x + dx[i]][cg1(y + dy[i])] &&
            u[x + dx[i]][cg2(y + c + dy[i])] &&
            (fa(pair<int, int>(x + dx[i], cg1(y + dy[i]))) ==
             fa(pair<int, int>(x + dx[j], cg2(y + c + dy[j]))))) {
          goto out;
        }
      }
    }
    u[x][y] = u[x][y + c] = 1;
    for (int i = 0; i < 8; i++) {
      if (!hf(x + dx[i])) continue;
      if (u[x + dx[i]][cg1(y + dy[i])])
        ad(pair<int, int>(x + dx[i], cg1(y + dy[i])), pair<int, int>(x, y));
      if (u[x + dx[i]][cg2(y + c + dy[i])])
        ad(pair<int, int>(x + dx[i], cg2(y + c + dy[i])),
           pair<int, int>(x, y + c));
    }
    cnt++;
  out:;
  }
  write(cnt);
  return 0;
}
