#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m, k, q, r, cnt, x;
  cin >> n >> m >> k;
  int i, j;
  i = 1, j = 1;
  int temp = k - 1;
  while (temp--) {
    cnt = 2;
    cout << cnt << " ";
    while (cnt--) {
      if (i & 1) {
        cout << i << " " << j << " ";
        j++;
        if (j == m + 1) i++, j = 1;
      } else {
        cout << i << " " << m + 1 - j << " ", j++;
        if (j == m + 1) i++, j = 1;
      }
    }
    cout << "\n";
  }
  cout << n * m - 2 * k + 2 << " ";
  while (i <= n) {
    while (j <= m) {
      if (i & 1)
        cout << i << " " << j << " ";
      else
        cout << i << " " << m + 1 - j << " ";
      j++;
    }
    i++, j = 1;
  }
  cout << "\n";
  return 0;
}
