#include <bits/stdc++.h>
using namespace std;
int n, m, k, x, y, p, LC;
int main() {
  scanf("%d%d%d", &m, &n, &k);
  x = k;
  for (int i = 1; i <= m; ++i)
    if (i % 2 == 1) {
      for (int j = 1; j <= n; ++j) {
        if (LC == p) {
          if (LC != 0) printf("\n");
          LC = 0;
          if (k > 1)
            p = 2;
          else
            p = m * n - 2 * (x - 1);
          --k;
          printf("%d ", p);
        }
        printf("%d %d ", i, j);
        ++LC;
      }
    } else
      for (int j = n; j >= 1; --j) {
        if (LC == p) {
          if (LC != 0) printf("\n");
          LC = 0;
          if (k > 1)
            p = 2;
          else
            p = m * n - 2 * (x - 1);
          --k;
          printf("%d ", p);
        }
        printf("%d %d ", i, j);
        ++LC;
      }
  fclose(stdin);
  fclose(stdout);
}
