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 R = 3005, C = 3005;
const int go[8][2] = {{1, 0},  {1, 1},   {1, -1}, {0, 1},
                      {0, -1}, {-1, -1}, {-1, 1}, {-1, 0}};
int par[3 * R * C], r, c, n;
int find(int x) { return par[x] < 0 ? x : par[x] = find(par[x]); }
void join(int x, int y) {
  x = find(x);
  y = find(y);
  if (x == y) return;
  if (par[x] < par[y]) {
    par[x] += par[y];
    par[y] = x;
  } else {
    par[y] += par[x];
    par[x] = y;
  }
}
int id(int x, int y) { return x * 2 * c + y + 1; }
vector<int> getneighbour(int x, int y) {
  vector<int> ans(0);
  for (int i = 0; i < 8; i++) {
    int x1 = x + go[i][0], y1 = (y + go[i][1] + 2 * c) % (2 * c);
    if (x1 >= 0 && x1 < r && par[id(x1, y1)] != 0) {
      ans.push_back(find(id(x1, y1)));
    }
  }
  return ans;
}
bool canadd(int x, int y) {
  vector<int> a = getneighbour(x, y);
  vector<int> b = getneighbour(x, y + c);
  for (int i = 0; i < a.size(); i++) {
    for (int j = 0; j < b.size(); j++) {
      if (a[i] == b[j]) return false;
    }
  }
  return true;
}
void addpoint(int x, int y) {
  for (int i = 0; i < 2; i++) {
    par[id(x, y + i * c)] = -1;
    vector<int> near = getneighbour(x, y + i * c);
    for (int j = 0; j < near.size(); j++) {
      join(id(x, y + i * c), near[j]);
    }
  }
}
int main() {
  scanf("%d%d%d", &r, &c, &n);
  if (c == 1) {
    printf("0\n");
    return 0;
  }
  int ans = 0;
  while (n--) {
    int x, y;
    scanf("%d%d", &x, &y);
    x--;
    y--;
    if (canadd(x, y)) {
      addpoint(x, y);
      ans++;
    }
  }
  printf("%d\n", ans);
  return 0;
}
