#include <bits/stdc++.h>
using namespace std;
signed main() {
  long long n, m, k;
  cin >> n >> m >> k;
  queue<pair<long long, long long> > q;
  for (long long x = 1; x <= n; x++) {
    for (long long y = 1; x % 2 == 1 && y <= m; y++) {
      q.push({x, y});
    }
    for (long long y = m; x % 2 == 0 && y >= 1; y--) {
      q.push({x, y});
    }
  }
  for (long long x = 1; x <= k - 1; x++) {
    cout << "2 ";
    pair<long long, long long> t = q.front();
    q.pop();
    cout << t.first << " " << t.second << " ";
    t = q.front();
    q.pop();
    cout << t.first << " " << t.second << " ";
    cout << "\n";
  }
  cout << q.size() << " ";
  while (!q.empty()) {
    pair<long long, long long> t = q.front();
    q.pop();
    cout << t.first << " " << t.second << " ";
  }
}
