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 read() {
  int s = 0, f = 1;
  char c = getchar();
  while (c < '0' || c > '9') {
    if (c == '-') f = 0;
    c = getchar();
  }
  while (c >= '0' && c <= '9')
    s = (s << 1) + (s << 3) + (c ^ 48), c = getchar();
  return f ? s : -s;
}
const int N = 1e7 + 10;
int r, c, n, ans, fa[N], vis[1010][2010];
int Hash(int x, int y) { return (x - 1) * c * 2 + y; }
int getfa(int x) { return fa[x] == x ? x : fa[x] = getfa(fa[x]); }
int dx[8] = {1, 0, -1, 0, 1, 1, -1, -1}, dy[8] = {0, 1, 0, -1, 1, -1, 1, -1};
bool check(int x, int y) {
  int sx = x, sy = y + c;
  for (register int i = 0; i < 8; ++i) {
    int nx = x + dx[i], ny = y + dy[i];
    if (ny < 1)
      ny = c * 2;
    else if (ny == c * 2 + 1)
      ny = 1;
    if (nx > 0 && nx <= r && vis[nx][ny]) {
      for (register int j = 0; j < 8; ++j) {
        int nx2 = sx + dx[j], ny2 = sy + dy[j];
        if (ny2 < 1)
          ny2 = c * 2;
        else if (ny2 == c * 2 + 1)
          ny2 = 1;
        if (nx2 > 0 && nx2 <= r && vis[nx2][ny2]) {
          if (getfa(Hash(nx, ny)) == getfa(Hash(nx2, ny2))) return 0;
        }
      }
    }
  }
  return 1;
}
void Del(int x, int y) {
  int sx = x, sy = y + c;
  for (register int i = 0; i < 8; ++i) {
    int nx = x + dx[i], ny = y + dy[i];
    if (ny == 0)
      ny = c * 2;
    else if (ny == c * 2 + 1)
      ny = 1;
    cout << "Gan: " << x << ' ' << y << ' ' << nx << ' ' << ny << '\n';
    if (nx > 0 && nx <= r && vis[nx][ny]) {
      int fax = getfa(Hash(nx, ny)), fay = getfa(Hash(x, y));
      fa[fay] = fax;
    }
    int nx2 = sx + dx[i], ny2 = sy + dy[i];
    if (ny2 == 0)
      ny2 = c * 2;
    else if (ny2 == c * 2 + 1)
      ny2 = 1;
    if (nx2 > 0 && nx2 <= r && vis[nx2][ny2]) {
      int fax = getfa(Hash(sx, sy)), fay = getfa(Hash(nx2, ny2));
      fa[fax] = fay;
    }
  }
  vis[x][y] = vis[sx][sy] = 1;
}
int main() {
  r = read();
  c = read();
  n = read();
  ans = 0;
  if (c == 1)
    puts("0");
  else {
    memset(vis, 0, sizeof vis);
    int ans = 0;
    for (register int i = 1; i <= r; ++i)
      for (register int j = 1; j <= 2 * c; ++j) fa[Hash(i, j)] = Hash(i, j);
    for (register int i = 1; i <= n; ++i) {
      int x = read(), y = read();
      if (check(x, y)) {
        Del(x, y), ++ans;
      }
    }
    printf("%d\n", ans);
  }
  return 0;
}
