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>
#pragma GCC optimize(2)
#pragma GCC optimize(3)
using namespace std;
template <typename T>
void ckmax(T &a, T b) {
  if (a < b) a = b;
}
template <typename T>
void ckmin(T &a, T b) {
  if (a > b) a = b;
}
inline int read() {
  int x = 0, neg = 1;
  char op = getchar();
  while (!isdigit(op)) {
    if (op == '-') neg = -1;
    op = getchar();
  }
  while (isdigit(op)) {
    x = 10 * x + op - '0';
    op = getchar();
  }
  return neg * x;
}
inline void print(int x) {
  if (x < 0) {
    putchar('-');
    x = -x;
  }
  if (x >= 10) print(x / 10);
  putchar(x % 10 + '0');
}
const int N = 18000001;
int tag[3001][6001];
int r, c, n, ans;
int id(int x, int y) { return (x - 1) * 2 * c + y; }
bool ok(int &x, int &y) {
  if (y == 0)
    y = 2 * c;
  else if (y == 2 * c + 1)
    y = 1;
  return (x >= 1 && x <= r && tag[x][y]);
}
int f[N];
int find(int x) { return f[x] == x ? x : f[x] = find(f[x]); }
void merge(int x, int y) {
  x = find(x), y = find(y);
  f[x] = y;
}
const int dx[] = {1, 0, -1, 0, 1, 1, -1, -1};
const int dy[] = {0, 1, 0, -1, 1, -1, 1, -1};
bool check(int x, int y) {
  int x1 = x, y1 = y + c;
  for (register int i = 0; i < 8; i++) {
    int fx = x + dx[i], fy = y + dy[i];
    if (!ok(fx, fy)) continue;
    for (register int j = 0; j < 8; j++) {
      int fx1 = x1 + dx[j], fy1 = y1 + dy[j];
      if (!ok(fx1, fy1)) continue;
      if (find(id(fx, fy)) == find(id(fx1, fy1))) {
        return false;
      }
    }
  }
  return true;
}
void del(int x, int y) {
  int x1 = x, y1 = y + c;
  for (register int i = 0; i < 8; i++) {
    int fx = x + dx[i], fy = y + dy[i];
    if (ok(fx, fy)) merge(id(fx, fy), id(x, y));
    int fx1 = x1 + dx[i], fy1 = y1 + dy[i];
    if (ok(fx1, fy1)) merge(id(fx1, fy1), id(x1, y1));
  }
  tag[x][y] = tag[x1][y1] = 1;
}
int main() {
  scanf("%d%d%d", &r, &c, &n);
  if (c == 1) {
    puts("0");
    exit(0);
  }
  for (register int i = 1; i <= r; i++) {
    for (register int j = 1; j <= 2 * c; j++) {
      f[id(i, j)] = id(i, j);
    }
  }
  while (n--) {
    int x, y;
    scanf("%d%d", &x, &y);
    if (check(x, y)) del(x, y), ans++;
  }
  printf("%d\n", ans);
  return 0;
}
