#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];
    }
  }
  for (int i = 1; i <= n; ++i) {
    id[i][0] = id[i][m << 1];
    id[i][m << 1 | 1] = id[i][1];
  }
  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;
}
