#include <bits/stdc++.h>
using namespace std;
int const MAXN = 1501;
int main() {
  (ios::sync_with_stdio(false));
  int n, m, k, k2;
  cin >> n >> m >> k;
  k2 = k;
  int dir = 0, i = 1, j = 1, p = 0;
  while (i >= 1 && i <= n && j >= 1 && j <= m) {
    if (k > 1 && (p == 0)) {
      cout << 2 << " ";
    }
    if (k == 1 && p == 0) cout << (m * n - (k2 - 1) * 2) << " ";
    cout << i << " " << j << " ";
    if (j == m & !dir) {
      dir = 1;
      i++;
    } else if (j == 1 && dir) {
      dir = 0;
      i++;
    } else if (dir)
      j--;
    else if (!dir)
      j++;
    p++;
    if (k > 1 && (p == 2)) {
      p = 0;
      k--;
      cout << '\n';
    }
  }
  return 0;
}
