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