#include <bits/stdc++.h>
int n, m, k, c = 1, j = 1, f, i = 1;
int main() {
  scanf("%d %d %d", &n, &m, &k);
  for (i; i <= n && c <= k - 1;) {
    if (f == 0 && c <= k - 1) {
      for (j; j <= m && c <= k - 1; j += 2) {
        if (j + 1 <= m) {
          c++;
          printf("%d %d %d %d %d\n", 2, i, j, i, j + 1);
        }
      }
      if (j != m + 1 && c <= k - 1) {
        c++;
        printf("%d %d %d %d %d\n", 2, i, m, i + 1, m);
        i++;
        j = m - 1;
        f = 1;
      } else if (j == m + 1 && c <= k - 1) {
        i++;
        j = m;
        f = 1;
      }
    }
    if (f == 1 && c <= k - 1) {
      for (j; j >= 1 && c <= k - 1; j -= 2) {
        if (j - 1 >= 1) {
          c++;
          printf("%d %d %d %d %d\n", 2, i, j, i, j - 1);
        }
      }
      if (j != 0 && c <= k - 1) {
        c++;
        printf("%d %d %d %d %d\n", 2, i, 1, i + 1, 1);
        j = 2;
        i++;
        f = 0;
      } else if (j == 0 && c <= k - 1) {
        i++;
        j = 1;
        f = 0;
      }
    }
    if (c == k) break;
  }
  printf("%d ", n * m - (k - 1) * 2);
  for (i; i <= n; i++) {
    if (f == 0) {
      for (j; j <= m; j++) printf("%d %d ", i, j);
      f = 1;
      j = m;
    } else {
      for (j; j >= 1; j--) printf("%d %d ", i, j);
      j = 1;
      f = 0;
    }
  }
}
