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, fa[20000050], rk[20000050];
bool exist[20000050];
stack<pair<int *, int> > stk;
int fnd(int x) { return fa[x] == x ? x : (fa[x] = fnd(fa[x])); }
void Union(int x, int y) {
  int fx = fnd(x), fy = fnd(y);
  if (fx == fy) return;
  if (rk[fx] <= rk[fy]) {
    stk.push(make_pair(&fa[fx], fa[fx]));
    fa[fx] = fy;
    if (rk[fx] == rk[fy]) stk.push(make_pair(&rk[fy], rk[fy])), rk[fy]++;
  } else if (rk[fx] > rk[fy]) {
    stk.push(make_pair(&fa[fy], fa[fy]));
    fa[fy] = fx;
  }
}
void Back(bool ndbk) {
  while (!stk.empty()) {
    if (ndbk) *(stk.top().first) = stk.top().second;
    stk.pop();
  }
}
const int drt[8][2] = {{1, 0}, {-1, 0},  {0, 1},  {0, -1},
                       {1, 1}, {-1, -1}, {-1, 1}, {1, -1}};
void Addblock(int x, int y) {
  for (int i = 0; i < 8; i++) {
    int tx = x + drt[i][0], ty = y + drt[i][1];
    if (ty < 0)
      ty += 2 * c;
    else if (ty >= 2 * c)
      ty -= 2 * c;
    if (tx > -1 && tx < r && exist[tx * 6000 + ty])
      Union(x * 6000 + y, tx * 6000 + ty);
  }
}
bool check(void) {
  int ri, ci;
  scanf("%d%d", &ri, &ci);
  --ri, --ci;
  exist[ri * 6000 + ci] = exist[ri * 6000 + c + ci] = true;
  Addblock(ri, ci);
  Addblock(ri, c + ci);
  if (fnd(ri * 6000 + ci) == fnd(ri * 6000 + c + ci)) {
    exist[ri * 6000 + ci] = exist[ri * 6000 + c + ci] = false;
    Back(true);
    return false;
  }
  Back(false);
  return true;
}
int main(int argc, char const *argv[]) {
  int n, ans = 0;
  scanf("%d%d%d", &r, &c, &n);
  for (int i = 0; i < r * 6000; i++) rk[i] = 1, fa[i] = i;
  memset(exist, 0, sizeof(exist));
  while (n--) ans += check();
  printf("%d\n", ans);
  return 0;
}
