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 = 3005;
const int M = (N * N) << 1;
const int dirx[8] = {1, 0, -1, 0, 1, 1, -1, -1};
const int diry[8] = {0, 1, 0, -1, 1, -1, 1, -1};
int f[M], vis[N][N << 1], r, c;
inline int read() {
  int x = 0, f = 1;
  char ch = getchar();
  while (!isdigit(ch)) {
    if (ch == '-') f = -1;
    ch = getchar();
  }
  while (isdigit(ch)) {
    x = x * 10 + ch - '0';
    ch = getchar();
  }
  return x * f;
}
inline int GetID(int x, int y) { return (x - 1) * c * 2 + y; }
inline bool Check(int &x, int &y) {
  if (y == 0)
    y = c * 2;
  else if (y == c * 2 + 1)
    y = 1;
  return x >= 1 && x <= r && vis[x][y];
}
inline int find(int x) {
  if (f[x] == x)
    return f[x];
  else
    f[x] = find(f[x]);
  return f[x];
}
inline bool check(int x, int y) {
  int X = x, Y = y + c;
  for (int i = 0; i < 8; i++) {
    int rx = x + dirx[i], ry = y + diry[i];
    if (!Check(rx, ry)) continue;
    for (int j = 0; j < 8; j++) {
      int cx = X + dirx[j], cy = Y + diry[j];
      if (!Check(cx, cy)) continue;
      if (find(GetID(rx, ry)) == find(GetID(cx, cy))) return 0;
    }
  }
  return 1;
}
inline void Merge(int x, int y) {
  int fx = find(x), fy = find(y);
  f[fx] = fy;
}
inline void GB(int x, int y) {
  int X = x, Y = y + c;
  for (int i = 0; i < 8; i++) {
    int rx = x + dirx[i], ry = y + diry[i];
    if (Check(rx, ry)) Merge(GetID(x, y), GetID(rx, ry));
    int cx = X + dirx[i], cy = Y + diry[i];
    if (Check(cx, cy)) Merge(GetID(X, Y), GetID(cx, cy));
  }
  vis[x][y] = vis[X][Y] = 1;
}
int main() {
  int n;
  r = read(), c = read(), n = read();
  if (c == 1) {
    puts("0");
    return 0;
  }
  for (int i = 1; i <= r; i++)
    for (int j = 1; j <= c * 2; j++) {
      f[GetID(i, j)] = GetID(i, j);
      vis[i][j] = 0;
    }
  int ans = 0;
  while (n--) {
    int x = read(), y = read();
    if (check(x, y)) {
      GB(x, y);
      ans++;
    }
  }
  printf("%d\n", ans);
  return 0;
}
