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 maxn = 3005;
const int maxm = maxn * maxn << 1;
int n, m, q;
int id[maxn][maxn << 1];
int fa[maxm];
int vis[maxm];
int top = 0;
stack<pair<int, int> > sta;
inline int getfa(int x) {
  sta.push(make_pair(x, fa[x]));
  return fa[x] == x ? x : fa[x] = getfa(fa[x]);
}
inline void bing(int x, int y) {
  if (vis[x] && vis[y]) {
    int fax = getfa(x);
    int fay = getfa(y);
    if (fax != fay) fa[fax] = fay;
  }
}
inline void Union(int x, int y) {
  int now = id[x][y];
  bing(id[x + 1][y], now);
  bing(id[x + 1][y - 1], now);
  bing(id[x + 1][y + 1], now);
  bing(id[x - 1][y], now);
  bing(id[x - 1][y - 1], now);
  bing(id[x - 1][y + 1], now);
  bing(id[x][y - 1], now);
  bing(id[x][y + 1], now);
}
inline void rm() {
  while (!sta.empty()) {
    fa[sta.top().first] = sta.top().second;
    sta.pop();
  }
}
int main() {
  scanf("%d%d%d", &n, &m, &q);
  int __cnt = 0;
  for (int i = 1; i <= n; ++i) {
    for (int j = 1; j <= (m << 1); ++j) {
      id[i][j] = ++__cnt;
      fa[id[i][j]] = id[i][j];
    }
  }
  int ans = 0;
  while (q--) {
    int x, y;
    scanf("%d%d", &x, &y);
    if (vis[id[x][y]]) continue;
    vis[id[x][y]] = vis[id[x][y + m]] = true;
    Union(x, y);
    Union(x, y + m);
    if (getfa(id[x][y]) == getfa(id[x][y + m])) {
      rm();
      vis[id[x][y]] = vis[id[x][y + m]] = false;
    } else
      ans++;
    while (!sta.empty()) sta.pop();
  }
  printf("%d\n", ans);
  return 0;
}
