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 N = 2e7 + 5;
int r, c, n, f[N], ans = 0;
const int dx[] = {1, -1, 1, -1, 1, -1, 0, 0};
const int dy[] = {1, -1, -1, 1, 0, 0, 1, -1};
bool del[3005][6005];
inline int id(int x, int y) { return (x - 1) * c * 2 + y; }
inline bool ok(int &x, int &y) {
  if (!y)
    y = c * 2;
  else if (y == c * 2 + 1)
    y = 1;
  return (x > 0 && x <= r && del[x][y]);
}
inline int find(int x) { return x == f[x] ? x : f[x] = find(f[x]); }
inline bool chk(int x, int y) {
  int x1 = x, y1 = y + c;
  for (register int i = (0); i <= (7); ++i) {
    int tx = x + dx[i], ty = y + dy[i];
    if (!ok(tx, ty)) continue;
    for (register int j = (0); j <= (7); ++j) {
      int nx = x1 + dx[j], ny = y1 + dy[j];
      if (!ok(nx, ny)) continue;
      if (find(id(tx, ty)) == find(id(nx, ny))) return 0;
    }
  }
  return 1;
}
inline void merge(int x, int y) {
  int r1 = find(x), r2 = find(y);
  f[r1] = r2;
}
inline void de(int x, int y) {
  int x1 = x, y1 = y + c;
  for (register int i = (0); i <= (7); ++i) {
    int nx = x + dx[i], ny = y + dy[i];
    if (ok(nx, ny)) merge(id(x, y), id(nx, ny));
    int rx = x1 + dx[i], ry = y1 + dy[i];
    if (ok(rx, ry)) merge(id(x1, y1), id(rx, ry));
  }
  del[x][y] = 1;
  del[x1][y1] = 1;
}
int main() {
  scanf("%d%d%d", &r, &c, &n);
  if (c == 1) return puts("0"), 0;
  for (register int i = (1); i <= (r); ++i)
    for (register int j = (1); j <= (c * 2); ++j) f[id(i, j)] = id(i, j);
  while (n--) {
    int x, y;
    scanf("%d%d", &x, &y);
    if (chk(x, y)) de(x, y), ++ans;
  }
  printf("%d\n", ans);
  return 0;
}
