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 NMax = 3100, MMax = 601000;
int N, M, C, father[MMax], use[MMax];
int dx[10] = {1, 1, -1, -1, 0, 0, 1, -1};
int dy[10] = {-1, 1, 1, -1, 1, -1, 0, 0};
vector<pair<int, int> > A;
map<pair<int, int>, int> S;
int Find(int a) {
  int R;
  for (R = a; father[R] != -1; R = father[R])
    ;
  int tmp;
  while (father[a] != -1) {
    tmp = father[a];
    father[a] = R;
    a = tmp;
  }
  return R;
}
void Union(int a, int b) {
  int first = Find(a), second = Find(b);
  if (first != second) father[first] = second;
}
int main() {
  scanf("%d%d%d", &N, &M, &C);
  for (int i = 1; i <= C; i++) {
    int first, second;
    scanf("%d%d", &first, &second);
    A.push_back(make_pair(first, second));
    S[make_pair(first, second)] = i;
    S[make_pair(first, second + M)] = C + i;
  }
  memset(father, -1, sizeof(father));
  int ret = 0;
  for (int i = 1; i <= C; i++) {
    int first = A[i - 1].first, second = A[i - 1].second;
    int flag = 0;
    for (int j = 0; j < 8 && !flag; j++)
      if (S[make_pair(first + dx[j], second + dy[j])] &&
          use[S[make_pair(first + dx[j], second + dy[j])]]) {
        for (int k = 0; k < 8; k++)
          if (S[make_pair(first + dx[k], second + M + dy[k])] &&
              use[S[make_pair(first + dx[k], second + M + dy[k])]] &&
              Find(S[make_pair(first + dx[j], second + dy[j])]) ==
                  Find(S[make_pair(first + dx[k], second + M + dy[k])])) {
            flag = 1;
            break;
          }
      }
    if (flag) continue;
    use[S[make_pair(first, second)]] = use[S[make_pair(first, second + M)]] = 1;
    for (int j = 0; j < 8; j++) {
      if (S[make_pair(first + dx[j], second + dy[j])] &&
          use[S[make_pair(first + dx[j], second + dy[j])]])
        Union(S[make_pair(first, second)],
              S[make_pair(first + dx[j], second + dy[j])]);
      if (S[make_pair(first + dx[j], second + M + dy[j])] &&
          use[S[make_pair(first + dx[j], second + M + dy[j])]])
        Union(S[make_pair(first, second + M)],
              S[make_pair(first + dx[j], second + M + dy[j])]);
    }
    ret++;
  }
  printf("%d\n", ret);
  getchar();
  getchar();
  return 0;
}
