#include <bits/stdc++.h>
using namespace std;
bool M[3000][6000];
int dr[] = {-1, -1, -1, 0, 0, 1, 1, 1};
int dc[] = {-1, 0, 1, -1, 1, -1, 0, 1};
int parent[18000000];
int Find(int x) {
  if (parent[x] != x) parent[x] = Find(parent[x]);
  return parent[x];
}
void Union(int x, int y) {
  x = Find(x);
  y = Find(y);
  parent[x] = y;
}
int R, C;
int id(int r, int c) { return r * 2 * C + c; }
int main() {
  int N, r, c;
  scanf("%d %d %d", &R, &C, &N);
  if (C == 1)
    printf("0\n");
  else {
    for (int i = R * 2 * C - 1; i >= 0; --i) parent[i] = i;
    int ans = 0;
    while (N--) {
      scanf("%d %d", &r, &c);
      --r;
      --c;
      bool add = true;
      for (int k1 = 0; k1 < 8; ++k1) {
        int r2 = r + dr[k1], c2 = c + dc[k1];
        if (c2 == -1) c2 = 2 * C - 1;
        if (c2 == 2 * C) c2 = 0;
        if (r2 >= 0 && r2 < R && M[r2][c2]) {
          int u = id(r2, c2);
          for (int k2 = 0; k2 < 8; ++k2) {
            int r3 = r + dr[k2], c3 = c + C + dc[k2];
            if (c3 == -1) c3 = 2 * C - 1;
            if (c3 == 2 * C) c3 = 0;
            if (r3 >= 0 && r3 < R && M[r3][c3]) {
              int v = id(r3, c3);
              if (Find(u) == Find(v)) add = false;
            }
          }
        }
      }
      if (add) {
        ++ans;
        M[r][c] = M[r][c + C] = true;
        for (int k = 0; k < 8; ++k) {
          int r2 = r + dr[k], c2 = c + dc[k];
          if (c2 == -1) c2 = 2 * C - 1;
          if (c2 == 2 * C) c2 = 0;
          if (r2 >= 0 && r2 < R && M[r2][c2]) Union(id(r, c), id(r2, c2));
        }
        for (int k = 0; k < 8; ++k) {
          int r2 = r + dr[k], c2 = c + C + dc[k];
          if (c2 == -1) c2 = 2 * C - 1;
          if (c2 == 2 * C) c2 = 0;
          if (r2 >= 0 && r2 < R && M[r2][c2]) Union(id(r, c + C), id(r2, c2));
        }
      }
    }
    printf("%d\n", ans);
  }
  return 0;
}
