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;
inline int getint() {
  int x = 0, c = getchar();
  for (; c < 48 || c > 57; c = getchar())
    ;
  for (; c > 47 && c < 58; x = x * 10 + c - 48, c = getchar())
    ;
  return x;
}
const int dx[] = {1, 1, 1, -1, -1, -1, 0, 0},
          dy[] = {-1, 0, 1, -1, 0, 1, -1, 1};
int n, m, q, p[3005 * 6005], s[3005 * 6005], ans, a[2][10], yy[2];
bool del[3005][6005], ss[2], tt[2];
int find(int x) { return x == p[x] ? x : p[x] = find(p[x]); }
void merge(int x, int y) {
  x = find(x), y = find(y);
  if (x == y) {
    return;
  }
  if (s[x] < s[y]) {
    swap(x, y);
  }
  p[y] = x;
  s[x] += s[x] == s[y];
}
int main() {
  scanf("%d%d%d", &n, &m, &q);
  if (m == 1) {
    puts("0");
    return 0;
  }
  yy[1] = m;
  m *= 2;
  int s = n * m + 1, t = s + 1;
  for (int i = 1; i <= t; ++i) {
    p[i] = i;
  }
  for (; q--;) {
    int x = getint(), y = getint();
    a[0][0] = a[1][0] = 0;
    ss[0] = ss[1] = tt[0] = tt[1] = 0;
    bool flag = 1;
    if (y == 1) {
      ss[0] = 1;
    }
    if (y == yy[1]) {
      tt[1] = 1;
    }
    for (int k = 0; k < 2 && flag; ++k) {
      if (ss[k] && tt[k]) {
        flag = 0;
      }
      for (int i = 0; i < 8 && flag; ++i) {
        int fx = dx[i] + x, fy = dy[i] + y + yy[k];
        if (fx < 1 || fy < 1 || fx > n || fy > m || !del[fx][fy]) {
          continue;
        }
        int hh = find(((fx - 1) * m + fy));
        a[k][++a[k][0]] = hh;
        if (hh == find(s)) {
          ss[k] = 1;
        }
        if (hh == find(t)) {
          tt[k] = 1;
        }
        if (ss[k] && tt[k]) {
          flag = 0;
        }
      }
    }
    if (flag && ss[0] && tt[1]) {
      for (int i = 0; i < a[0][0] && flag; ++i) {
        for (int j = 0; j < a[1][0] && flag; ++j) {
          if (a[0][i] == a[1][j]) {
            flag = 0;
          }
        }
      }
    }
    if (flag) {
      if (ss[0]) {
        merge(s, ((x - 1) * m + y));
      }
      if (tt[0]) {
        merge(t, ((x - 1) * m + y));
      }
      if (ss[1]) {
        merge(s, ((x - 1) * m + y + yy[1]));
      }
      if (tt[1]) {
        merge(t, ((x - 1) * m + y + yy[1]));
      }
      if (a[0][0]) {
        merge(((x - 1) * m + y), a[0][1]);
      }
      for (int i = 1; i < a[0][0]; ++i) {
        merge(a[0][i - 1], a[0][i]);
      }
      if (a[1][0]) {
        merge(((x - 1) * m + y + m), a[1][1]);
      }
      for (int i = 1; i < a[1][0]; ++i) {
        merge(a[1][i - 1], a[1][i]);
      }
      ++ans;
      del[x][y] = 1;
      del[x][y + yy[1]] = 1;
    }
  }
  cout << ans;
  return 0;
}
