#include <bits/stdc++.h>
using namespace std;
vector<pair<int, int> > g[int(1e5)];
int main() {
  int n, m, k;
  cin >> n >> m >> k;
  int x = 0;
  for (int i = 1; i <= n; i++) {
    if (i & 1) {
      for (int j = 1; j <= m; j++) {
        if (g[x].size() == 2 && x < k - 1) x++;
        g[x].push_back({i, j});
      }
    } else {
      for (int j = m; j > 0; j--) {
        if (g[x].size() == 2 && x < k - 1) x++;
        g[x].push_back({i, j});
      }
    }
  }
  for (int i = 0; i < k; i++) {
    cout << g[i].size() << " ";
    for (int j = 0; j < g[i].size(); j++) {
      cout << g[i][j].first << " " << g[i][j].second << " ";
    }
    cout << endl;
  }
}
