#include <bits/stdc++.h>
using namespace std;
char s[10];
int main() {
  {
    long long n, m, k;
    cin >> n >> m >> k;
    long long t = n * m;
    int x = 1, y = 1;
    for (int i = 1; i < k; i++) {
      int p = t / k;
      cout << p << " ";
      while (p--) {
        cout << x << " " << y << " ";
        if (x % 2 == 1 && y == m) {
          x++;
        } else if (x % 2 == 0 && y == 1) {
          x++;
        } else if (x % 2 == 1)
          y++;
        else
          y--;
      }
      cout << endl;
    }
    cout << (t / k + t % k) << " ";
    while (x <= n || y <= m) {
      cout << x << " " << y << " ";
      if (x % 2 == 1 && x == n && y == m) break;
      if (x % 2 == 0 && x == n && y == 1) break;
      if (x % 2 == 1 && y == m) {
        x++;
      } else if (x % 2 == 0 && y == 1) {
        x++;
      } else if (x % 2 == 1)
        y++;
      else
        y--;
    }
  }
}
