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;
int r, c, n;
int land[3002][6004];
pair<int, int> ro[3002][6004];
pair<int, int> find(int x, int y) {
  return (ro[x][y].first == x and ro[x][y].second == y
              ? make_pair(x, y)
              : ro[x][y] = find(ro[x][y].first, ro[x][y].second));
}
vector<pair<int, int> > getn(int x, int y) {
  vector<pair<int, int> > v;
  for (int i = -1; i <= 1; i++) {
    for (int j = -1; j <= 1; j++) {
      int dx = x + i, dy = y + j;
      if (dx < 0 or dx >= r) continue;
      if (dy < 0 or dy >= 2 * c) continue;
      if (land[dx][dy] == 1) v.push_back(find(dx, dy));
    }
  }
  return v;
}
int check(int x, int y) {
  vector<pair<int, int> > v1 = getn(x, y);
  vector<pair<int, int> > v2 = getn(x, y + c);
  for (int i = 0; i < v1.size(); i++) {
    for (int j = 0; j < v2.size(); j++) {
      if (v1[i] == v2[j]) return 0;
    }
  }
  return 1;
}
void add(int x, int y) {
  land[x][y] = 1;
  ro[x][y] = make_pair(x, y);
  for (int i = -1; i <= 1; i++) {
    for (int j = -1; j <= 1; j++) {
      int dx = x + i, dy = y + j;
      if (dx < 0 or dx >= r) continue;
      if (dy < 0 or dy >= 2 * c) continue;
      if (land[dx][dy] == 1)
        ro[find(dx, dy).first][find(dx, dy).second] = ro[x][y];
    }
  }
}
int main() {
  cin >> r >> c >> n;
  if (c == 1) {
    cout << 0;
    return 0;
  }
  while (n--) {
    int kx, ky;
    scanf("%d %d", &kx, &ky);
    kx--, ky--;
    if (check(kx, ky) == 1) add(kx, ky), add(kx, ky + c);
  }
  int s = 0;
  for (int i = 0; i < r; i++) {
    for (int j = 0; j < c; j++) {
      s += land[i][j];
    }
  }
  cout << s << endl;
  return 0;
}
