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;
template <typename T>
inline T read(register T& t) {
  register T f = 1;
  register char ch = getchar();
  t = 0;
  while (ch < '0' || ch > '9') {
    if (ch == '-') f = -f;
    ch = getchar();
  }
  while (ch >= '0' && ch <= '9') t = t * 10 + ch - '0', ch = getchar();
  t *= f;
  return t;
}
template <typename T, typename... Args>
inline void read(T& t, Args&... args) {
  read(t);
  read(args...);
}
const long long p = 998244353;
inline long long power(register long long x, register long long k = p - 2) {
  register long long re = 1;
  for (; k; k >>= 1, x = x * x % p)
    if (k & 1) re = re * x % p;
  return re;
}
int r, c, n;
int fa[18000005];
inline int find(int x) {
  if (fa[x] == x) return x;
  return fa[x] = find(fa[x]);
}
bool del[3005][6005];
int Xx[] = {-1, -1, -1, 0, 1, 1, 1, 0};
int Yy[] = {-1, 0, 1, 1, 1, 0, -1, -1};
inline bool check(int R, int C) {
  for (int i = 0; i < 8; i++) {
    int Xr = R + Xx[i], Xc = C + Yy[i];
    if (Xr < 0 || Xr > R) continue;
    Xc = (Xc + 2 * c) % (2 * c);
    if (del[Xr][Xc] == 0) continue;
    for (int j = 0; j < 8; j++) {
      int Yr = R + Xx[j], Yc = C + c + Yy[j];
      if (Yr < 0 || Yr > R) continue;
      Yc = (Yc + 2 * c) % (2 * c);
      if (del[Yr][Yc] == 0) continue;
      if (find((((Xr)-1) * c + (Xc))) == find((((Yr)-1) * c + (Yc)))) return 0;
    }
  }
  return 1;
}
inline void merge(int R, int C) {
  for (int i = 0; i < 8; i++) {
    int Xr = R + Xx[i], Xc = C + Yy[i];
    if (Xr < 0 || Xr > R) continue;
    Xc = (Xc + 2 * c) % (2 * c);
    if (del[Xr][Xc] == 0) continue;
    int fat = find((((Xr)-1) * c + (Xc))), fbt = find((((R)-1) * c + (C)));
    if (fat == fbt) continue;
    fa[fat] = fbt;
  }
}
int main() {
  read(r, c, n);
  if (c == 1) return printf("0\n"), 0;
  for (int i = 1; i <= r * c * 2; i++) fa[i] = i;
  int ans = 0;
  while (n--) {
    int R, C;
    read(R, C);
    if (check(R, C) == 0) continue;
    del[R][C] = del[R][C + c] = 1;
    merge(R, C);
    merge(R, C + c);
    ans++;
  }
  printf("%d\n", ans);
  return 0;
}
