#include <bits/stdc++.h>
using namespace std;
inline int read() {
  int x = 0, f = 1;
  char c = getchar();
  while (c < '0' || c > '9') {
    if (c == '-') f = -1;
    c = getchar();
  }
  while (c >= '0' && c <= '9')
    x = (x << 3) + (x << 1) + (c ^ '0'), c = getchar();
  return x * f;
}
const int N = 3e3 + 5;
int a[N][N << 1], r, c, n;
int dx[8] = {0, 0, 1, -1, 1, 1, -1, -1};
int dy[8] = {1, -1, 0, 0, 1, -1, 1, -1};
int f[N * N << 1];
inline int get(int x) { return x == f[x] ? x : f[x] = get(f[x]); }
inline void Union(int x, int y) {
  int fx = get(x), fy = get(y);
  f[fx] = fy;
}
inline int ya(int x, int y) { return (x - 1) * c * 2 + y; }
inline int ok(int &x, int &y) {
  if (y < 1)
    y = c << 1;
  else if (y > (c << 1))
    y = 1;
  return x >= 1 && x <= r && a[x][y];
}
inline int check(int ax, int ay) {
  int bx = ax, by = ay + c;
  for (int i = 0; i < 8; i++) {
    int Ax = ax + dx[i], Ay = ay + dy[i];
    if (!ok(Ax, Ay)) continue;
    for (int j = 0; j < 8; j++) {
      int Bx = bx + dx[j], By = by + dy[j];
      if (!ok(Bx, By)) continue;
      if (get(ya(Ax, Ay)) == get(ya(Bx, By))) return 0;
    }
  }
  return 1;
}
inline void del(int ax, int ay) {
  int bx = ax, by = ay + c;
  for (int i = 0; i < 8; i++) {
    int Ax = ax + dx[i], Ay = ay + dy[i];
    if (ok(Ax, Ay)) Union(ya(ax, ay), ya(Ax, Ay));
    int Bx = bx + dx[i], By = by + dy[i];
    if (ok(Bx, By)) Union(ya(bx, by), ya(Bx, By));
  }
  a[ax][ay] = a[bx][by] = 1;
}
inline void solve() {
  r = read(), c = read(), n = read();
  if (c == 1) return puts("0"), void();
  int ans = 0;
  for (int i = 1; i <= r; i++)
    for (int j = 1; j <= c << 1; j++) f[ya(i, j)] = ya(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);
}
int main() {
  solve();
  return 0;
}
