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 = 3000 + 5, C = 3000 + 5, N = 300000 + 5, ND = N * 2;
int r, c, n;
int nd[R][C * 2];
int nwnd;
int fa[ND], sz[ND];
int *cat[ND], clstv[ND], nwc;
inline int newnd() {
  ++nwnd;
  fa[nwnd] = nwnd;
  sz[nwnd] = 1;
  return nwnd;
}
inline void ch(int &a, int b) {
  ++nwc;
  cat[nwc] = &a;
  clstv[nwc] = a;
  a = b;
}
inline void restore() {
  while (nwc) {
    *cat[nwc] = clstv[nwc];
    --nwc;
  }
}
inline void store() { nwc = 0; }
inline int gnd(int x, int y) {
  if (!nd[x][y]) ch(nd[x][y], newnd());
  return nd[x][y];
}
inline int find(int a) {
  int s = a, t;
  while (fa[s] != s) s = fa[s];
  while (fa[a] != s) t = fa[a], ch(fa[a], s), a = t;
  return s;
}
inline void uni(int a, int b) {
  a = find(a), b = find(b);
  if (a == b) return;
  if (sz[a] < sz[b]) swap(a, b);
  ch(sz[a], sz[a] + sz[b]);
  ch(fa[b], a);
}
const int pc[8][2] = {{0, 1}, {0, -1}, {1, 0},  {-1, 0},
                      {1, 1}, {1, -1}, {-1, 1}, {-1, -1}};
inline void insnd(int x, int y) {
  int u = gnd(x, y);
  for (int p = 0; p < 8; ++p) {
    int x2 = x + pc[p][0], y2 = y + pc[p][1];
    if (y2 <= 0) y2 += 2 * c;
    if (y2 > 2 * c) y2 -= 2 * c;
    if (nd[x2][y2]) uni(u, nd[x2][y2]);
  }
}
int main() {
  scanf("%d%d%d", &r, &c, &n);
  int ans = 0;
  while (n--) {
    int x, y;
    scanf("%d%d", &x, &y);
    insnd(x, y);
    insnd(x, c + y);
    if (find(nd[x][y]) == find(nd[x][c + y]))
      restore();
    else
      store(), ++ans;
  }
  printf("%d\n", ans);
  return 0;
}
