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 MAX = 3010;
const int dr[8] = {1, 0, -1, 0, 1, 1, -1, -1};
const int dc[8] = {0, 1, 0, -1, 1, -1, 1, -1};
int R, C, N;
bool land[MAX][2 * MAX];
int ds[2 * MAX * MAX];
int find(int x) { return ds[x] == x ? x : ds[x] = find(ds[x]); }
void merge(int x, int y) { ds[find(x)] = find(y); }
bool valid(int r, int c) {
  return r >= 0 && r < R && c >= 0 && c < 2 * C && land[r][c];
}
int get(int r, int c) { return find(r * 2 * C + c); }
void add(int r, int c) {
  for (int i = (0); i < (8); ++i) {
    int rr = r + dr[i];
    int cc = c + dc[i];
    if (valid(rr, cc)) merge(get(r, c), get(rr, cc));
  }
  land[r][c] = true;
}
int main() {
  scanf("%d%d%d", &R, &C, &N);
  ++R;
  for (int i = (0); i < (2 * R * C); ++i) ds[i] = i;
  int ans = 0;
  for (int k = (0); k < (N); ++k) {
    int r, c;
    scanf("%d%d", &r, &c);
    --c;
    set<int> A, B;
    for (int i = (0); i < (8); ++i) {
      int rr = r + dr[i];
      int cc = c + dc[i];
      if (valid(rr, cc)) A.insert(get(rr, cc));
      if (valid(rr, cc + C)) B.insert(get(rr, cc + C));
    }
    bool ok = true;
    for (int x : A)
      if (B.count(x)) ok = false;
    if (ok) {
      ++ans;
      add(r, c);
      add(r, c + C);
    }
  }
  printf("%d\n", C == 1 ? 0 : ans);
  return 0;
}
