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 = 3010;
int r, c, n, f[N * N * 2];
bool d[N][N * 2];
inline int getd(int x, int y) { return (x - 1) * c * 2 + y; }
inline int getf(int x) { return x == f[x] ? x : f[x] = getf(f[x]); }
int dx[8] = {0, 0, 1, 1, 1, -1, -1, -1};
int dy[8] = {1, -1, 0, 1, -1, 0, 1, -1};
bool Judge(int &x, int &y) {
  if (!y)
    y = c * 2;
  else if (y > c * 2)
    y = 1;
  return (x > 0 && x <= r && d[x][y]);
}
bool judge(int x, int ya) {
  int yb = ya + c, st = 0, s[9], nx, ny;
  for (int i = 0; i < 8; i++)
    if (Judge(nx = x + dx[i], ny = ya + dy[i])) s[++st] = getf(getd(nx, ny));
  for (int i = 0, S; i < 8; i++)
    if (Judge(nx = x + dx[i], ny = yb + dy[i])) {
      S = getf(getd(nx, ny));
      for (int j = 1; j <= st; j++)
        if (s[j] == S) return 0;
    }
  return 1;
}
inline void add(int x, int y) {
  x = getf(x), y = getf(y);
  f[y] = x;
}
void del(int x, int ya) {
  int yb = ya + c, ia = getd(x, ya), ib = getd(x, yb);
  for (int i = 0, nx, ny; i < 8; i++) {
    nx = x + dx[i], ny = ya + dy[i];
    if (Judge(nx, ny)) add(ia, getd(nx, ny));
    nx = x + dx[i], ny = yb + dy[i];
    if (Judge(nx, ny)) add(ib, getd(nx, ny));
  }
  d[x][ya] = d[x][yb] = 1;
}
inline int read() {
  register int x = 0;
  register char c;
  while (!isdigit(c = getchar()))
    ;
  do x = (x << 3) + (x << 1) + (c ^ 48);
  while (isdigit(c = getchar()));
  return x;
}
int main() {
  scanf("%d%d%d", &r, &c, &n);
  if (c <= 1) {
    puts("0");
    return 0;
  }
  for (int i = 1; i <= r * c * 2; i++) f[i] = i;
  int ans = 0, x, y;
  while (n--) {
    x = read(), y = read();
    if (judge(x, y)) ans++, del(x, y);
  }
  printf("%d", ans);
  return 0;
}
