#include <bits/stdc++.h>
using namespace std;
const int NN = 6005, fx[9] = {-1, -1, -1, 0, 0, 0, 1, 1, 1},
          fy[9] = {-1, 0, 1, -1, 0, 1, -1, 0, 1};
int n, m, q, ans, fa[NN * NN], a[NN][NN];
int read() {
  int x = 0;
  char ch = getchar();
  while (ch < '0' || ch > '9') ch = getchar();
  while (ch >= '0' && ch <= '9') x = x * 10 + ch - '0', ch = getchar();
  return x;
}
int id(int x, int y) {
  return (x - 1) * 2 * m + (y > 2 * m ? 1 : (y < 1 ? 2 * m : y));
}
int get(int x) { return x == fa[x] ? x : fa[x] = get(fa[x]); }
bool check(int x, int y) {
  return 1 <= x && x <= n && a[x][(y > 2 * m ? 1 : (y < 1 ? 2 * m : y))];
}
int main() {
  n = read(), m = read(), q = read();
  for (int i = (1); i <= (2 * n * m); i++) fa[i] = i;
  while (q--) {
    int x = read(), y = read(), z = y + m, fl = 1;
    a[x][y] = a[x][z] = 1;
    ans++;
    for (int i = (0); i <= (8); i++)
      if (fl)
        if (check(x + fx[i], y + fy[i]))
          for (int j = (0); j <= (8); j++)
            if (fl)
              if (check(x + fx[j], z + fy[j]))
                if (get(id(x + fx[i], y + fy[i])) ==
                    get(id(x + fx[j], z + fy[j])))
                  fl = 0;
    if (!fl) {
      a[x][y] = a[x][z] = 0;
      ans--;
      continue;
    }
    for (int i = (0); i <= (8); i++)
      if (check(x + fx[i], y + fy[i]))
        fa[get(id(x + fx[i], y + fy[i]))] = get(id(x, y));
    for (int i = (0); i <= (8); i++)
      if (check(x + fx[i], z + fy[i]))
        fa[get(id(x + fx[i], z + fy[i]))] = get(id(x, z));
  }
  printf("%d\n", ans);
  return 0;
}
