#include <bits/stdc++.h>
using namespace std;
int main() {
  long long int n, m, kparts;
  cin >> n >> m >> kparts;
  vector<pair<long long int, long long int> > A, B;
  for (int i = 1; i <= n; i++) {
    B.clear();
    for (int j = 1; j <= m; j++) {
      B.push_back(make_pair(i, j));
    }
    if (i & 1) {
      A.insert(A.end(), B.begin(), B.end());
    } else {
      reverse(B.begin(), B.end());
      A.insert(A.end(), B.begin(), B.end());
    }
  }
  long long int ind = 0;
  for (int i = 1; i <= kparts - 1; i++) {
    cout << 2 << " " << A[ind].first << " " << A[ind].second << " "
         << A[ind + 1].first << " " << A[ind + 1].second << "\n";
    ind += 2;
  }
  cout << n * m - ind << " ";
  for (int i = ind; i < n * m; i++) {
    cout << A[i].first << " " << A[i].second << " ";
  }
  return 0;
}
