#include <bits/stdc++.h>
using namespace std;
const int N = 3000 + 3;
const int d[8][2] = {{-1, -1}, {-1, 0}, {-1, 1}, {0, -1},
                     {0, 1},   {1, -1}, {1, 0},  {1, 1}};
int n, m, cases, tot, ans, fa[N * N << 1], f[N * N << 1];
bool g[N][N << 1];
inline int CNT(int x, int y) { return ((x - 1) * m << 1) + y; }
inline int getfa(int x) { return x == fa[x] ? x : (fa[x] = getfa(fa[x])); }
inline void merge(int x, int y) { fa[getfa(x)] = getfa(y); }
int main(int argc, char **argv) {
  int x, y, tx, ty, pos;
  bool flag;
  scanf("%d%d%d", &n, &m, &cases);
  tot = n * m;
  for (int i = 1; i <= (tot << 1); ++i) fa[i] = i;
  for (int t = 1; t <= cases; ++t) {
    scanf("%d%d", &x, &y);
    pos = CNT(x, y);
    flag = 1;
    for (int i = 0; i < 8; ++i) {
      tx = x + d[i][0];
      ty = y + d[i][1];
      if (ty < 1) ty += m << 1;
      if (tx < 1 || tx > n || !g[tx][ty]) continue;
      f[getfa(CNT(tx, ty))] = t;
    }
    for (int i = 0; i < 8; ++i) {
      tx = x + d[i][0];
      ty = y + m + d[i][1];
      if (ty > (m << 1)) ty -= m << 1;
      if (tx < 1 || tx > n || !g[tx][ty]) continue;
      if (f[getfa(CNT(tx, ty))] == t) {
        flag = 0;
        break;
      }
    }
    if (flag && m > 1) {
      ++ans;
      g[x][y] = g[x][y + m] = 1;
      for (int i = 0; i < 8; ++i) {
        tx = x + d[i][0];
        ty = y + d[i][1];
        if (ty < 1) ty += m << 1;
        if (tx < 1 || tx > n || !g[tx][ty]) continue;
        merge(CNT(tx, ty), pos);
      }
      for (int i = 0; i < 8; ++i) {
        tx = x + d[i][0];
        ty = y + m + d[i][1];
        if (ty > (m << 1)) ty -= m << 1;
        if (tx < 1 || tx > n || !g[tx][ty]) continue;
        merge(CNT(tx, ty), CNT(x, y + m));
      }
    }
  }
  printf("%d\n", ans);
  return 0;
}
