game played with small, rectangular blocks of wood or other material,
each identified by a number of dots, or pips, on its face. The blocks
usually are called bones, dominoes, or pieces and sometimes men, stones,
or even cards.
The face of each piece is divided, by a line or ridge, into two squares,
each of which is marked as would be a pair of dice...
The principle in nearly all modern dominoes games is to match one end
of a piece to another that is identically or reciprocally numbered.
Consider an arbitrary set of domino pieces where each piece is marked
with two digits from 1 to 6. Some sets can be completely laid
out in a row matching one end of a piece to another that is identically
numbered, while others cannot. For example, the set consisting of 5 pieces:
(1, 5), (1, 6), (5, 5) and (2, 4) twice, cannot
be laid out in a row. However, if we add (2, 5) piece to the above
set we could lay out the resulting set in the following row:
However, we are interested in a row having the smallest sum of digits on
its pieces. In our example, instead of the piece (2, 5) with a sum of 7,
we could add two pieces (1, 2) with a total sum of 6 to
lay out the following row:
Your task is to write a program that for a given domino set will find an additional
(possibly empty) set with the smallest possible sum of digits, so that a row could be
laid out with both sets combined.
The first line contains a single integer N representing the total
number of pieces in the domino set (2 ≤ N ≤ 100). The following N lines describe
pieces. Each piece is represented on a separate line in a form of two digits
from 1 to 6 separated by a space. The digits of a piece can be written in
On the first line write the smallest sum of digits of the additional set or 0 if
that set is empty. On the second line write the total number of pieces in the additional set or 0 if that set is empty. Then write the pieces of the additional set in the same format as in input.
If there are a number of additional sets with the same smallest sum of digits exist then write any one of them.
Problem Source: 2000-2001 ACM Northeastern European Regional Programming Contest