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>
int w[3001][3001], R, C, n, p[300001];
bool v[300001];
int find(int a) {
  if (p[a] == a) return a;
  return p[a] = find(p[a]);
}
int main() {
  int i, a, b, j, k, jj, kk, x, y, Res = 0;
  scanf("%d%d%d", &R, &C, &n);
  if (C == 1) {
    printf("0\n");
    return 0;
  }
  for (i = 1; i <= n; i++) {
    scanf("%d%d", &a, &b);
    if (C == 2) {
      for (j = a - 1; j <= a + 1; j++) {
        if (w[j][b % 2 + 1]) break;
      }
      if (j == a + 2) Res++, w[a][b] = i;
      continue;
    }
    w[a][b] = i;
    p[i] = i;
    for (j = a - 1; j <= a + 1; j++) {
      for (k = b - 1; k <= b + 1; k++) {
        kk = k;
        if (!k) kk = C;
        if (k == C + 1) kk = 1;
        if (!w[j][kk]) continue;
        v[find(w[j][kk])] = true;
      }
    }
    for (j = 1; j <= R; j++) {
      if (!w[j][1]) continue;
      x = find(w[j][1]);
      if (!v[x]) continue;
      for (k = j - 1; k <= j + 1; k++) {
        if (!w[k][C]) continue;
        y = find(w[k][C]);
        if (v[y]) break;
      }
      if (k != j + 2) break;
    }
    if (j == R + 1) {
      for (j = a - 1; j <= a + 1; j++) {
        for (k = b - 1; k <= b + 1; k++) {
          kk = k;
          if (!k) kk = C;
          if (k == C + 1) kk = 1;
          if (!w[j][kk]) continue;
          x = find(w[j][kk]), y = find(i);
          if (x != y) p[y] = x;
        }
      }
      Res++;
    } else
      v[w[a][b]] = false, w[a][b] = 0;
    for (j = a - 1; j <= a + 1; j++) {
      for (k = b - 1; k <= b + 1; k++) {
        kk = k;
        if (!k) kk = C;
        if (k == C + 1) kk = 1;
        if (!w[j][kk]) continue;
        v[w[j][kk]] = false;
      }
    }
  }
  printf("%d\n", Res);
}
