#include <bits/stdc++.h>
using namespace std;
int n, m, k;
void print(int a, int b) {
  printf("%d %d ", a, b);
  return;
}
int main() {
  scanf("%d%d%d", &n, &m, &k);
  int dir = 1, x = 1, y = 1;
  for (int i = 1; i <= k - 1; i++) {
    printf("2 ");
    if (dir == 1) {
      if (y <= m - 1) {
        print(x, y);
        print(x, y + 1);
        y += 2;
        if (y == m + 1) y = m, x++, dir = 2;
      } else
        print(x, y), print(x + 1, y), x++, y--, dir = 2;
    } else {
      if (y >= 2) {
        print(x, y);
        print(x, y - 1);
        y -= 2;
        if (y == 0) x++, y = 1, dir = 1;
      } else
        print(x, y), print(x + 1, y), x++, y++, dir = 1;
    }
    puts("");
  }
  int cnt = n * m - 2 * (k - 1);
  printf("%d ", cnt);
  while (cnt >= 1) {
    if (dir == 1) {
      print(x, y);
      y++;
      if (y > m) x++, y = m, dir = 2;
    } else {
      print(x, y);
      y--;
      if (y == 0) x++, y = 1, dir = 1;
    }
    cnt--;
  }
  puts("");
  return 0;
}
