2 5 10
2 2
1 1
1 4
2 1
1 2
1 5
2 4
2 5
1 3
2 3
 2 2 2
1 1
2 2
 3 3 9
1 1
1 2
1 3
2 1
2 2
2 3
3 1
3 2
3 3
 7 5 35
5 3
3 5
1 1
2 5
6 4
7 2
5 1
3 4
6 5
7 3
4 1
2 2
4 2
2 4
4 3
3 3
6 1
1 2
4 5
1 3
2 1
5 5
7 5
7 1
6 2
1 4
1 5
3 2
4 4
5 2
2 3
6 3
7 4
5 4
3 1
 1 5 4
1 1
1 2
1 4
1 5
 1 1 1
1 1
 5 7 21
4 4
4 5
5 5
5 6
5 7
5 1
5 2
4 2
3 2
3 1
3 7
3 6
2 6
1 6
1 7
1 1
1 2
1 3
1 4
2 4
3 4
 2 1 1
1 1
 2 2 4
2 1
1 1
1 2
2 2
 3000 3000 1
2222 738
 5 7 35
1 2
2 3
5 1
5 7
4 4
5 3
3 1
2 6
4 5
2 7
4 1
2 1
2 2
1 7
5 6
3 6
4 6
1 6
1 1
3 3
3 4
4 2
2 5
5 5
3 5
2 4
1 5
1 3
4 3
5 4
1 4
3 7
4 7
3 2
5 2
 5 4 1
4 1
 3 4 12
2 3
3 2
2 2
2 1
1 2
3 1
1 4
1 3
3 3
2 4
3 4
1 1
 3 3 3
1 1
2 2
3 3

8
 1
 6
 26
 4
 0
 20
 0
 2
 1
 28
 1
 9
 3

#include <bits/stdc++.h>
using namespace std;
const int MaxN = 4000;
int T, r, c, n, cnt, ans, f[MaxN * MaxN * 2], pd[MaxN][MaxN];
int dx[10] = {0, 0, 0, 1, -1, 1, 1, -1, -1},
    dy[10] = {0, 1, -1, 0, 0, 1, -1, 1, -1};
int getf(int x) { return x == f[x] ? x : f[x] = getf(f[x]); }
int genb(int x, int y) { return (x - 1) * 2 * c + y; }
int check(int x, int y) {
  for (int i = 1; i <= 8; ++i) {
    int fx = x + dx[i], fy = y + dy[i];
    if (fy == 0) fy = 2 * c;
    if (fx < 0 || fx > r || pd[fx][fy] == 0) continue;
    int nb = genb(fx, fy), ffx = getf(nb);
    for (int j = 1; j <= 8; ++j) {
      int fx = x + dx[j], fy = y + c + dy[j];
      if (fy > 2 * c) fy = 1;
      if (fx < 0 || fx > r || pd[fx][fy] == 0) continue;
      int nb = genb(fx, fy), fxx = getf(nb);
      if (fxx == ffx) return 0;
    }
  }
  return 1;
}
int main() {
  int x, y;
  scanf("%d%d%d", &r, &c, &n);
  cnt = 0;
  ans = 0;
  for (int i = 1; i <= r; ++i)
    for (int j = 1; j <= 2 * c; ++j) f[++cnt] = cnt;
  for (int i = 1; i <= n; ++i) {
    scanf("%d%d", &x, &y);
    if (check(x, y)) {
      pd[x][y] = 1;
      pd[x][y + c] = 1;
      ++ans;
      for (int j = 1; j <= 8; ++j) {
        int fx = x + dx[j], fy = y + dy[j];
        if (fy == 0) fy = 2 * c;
        if (fx < 0 || fx > r || pd[fx][fy] == 0) continue;
        int nb = genb(fx, fy), nbb = genb(x, y), ffx = getf(nb),
            ffy = getf(nbb);
        f[ffx] = ffy;
      }
      y += c;
      for (int j = 1; j <= 8; ++j) {
        int fx = x + dx[j], fy = y + dy[j];
        if (fy > 2 * c) fy = 1;
        if (fx < 0 || fx > r || pd[fx][fy] == 0) continue;
        int nb = genb(fx, fy), nbb = genb(x, y), ffx = getf(nb),
            ffy = getf(nbb);
        f[ffx] = ffy;
      }
    }
  }
  if (c == 1) {
    puts("0");
    return 0;
  }
  printf("%d\n", ans);
  return 0;
}
