A train station needs your help to maximize its efficiency. The train station can only have 100 train carts parked on a track at once, and it is imperative that the tracks are fully filled as to maximize profit. Given a list of trains and their lengths (number of train carts) print the pairs of trains that will most effectively fill the station.
You will be given 4 integers separated by spaces. Each of these integers represents the number of cars on a train.
Print the pairs of trains.
In the first case, Train 1 must be combined with Train 4, as 25 cars plus 75 cars adds up to 100 cars. Train 3 must be combined with Train 4, as 50 cars plus 50 cars equals 100 cars.
Also, assume that there is always a way to fill each track with 100 trains. Make sure the output format puts the trains in ascending order (i.e. Train 1 and Train 3, not Train 3 and Train 1).
## Input
You will be given 4 integers separated by spaces. Each of these integers represents the number of cars on a train.
## Output
Print the pairs of trains.
[samples]
## Note
In the first case, Train 1 must be combined with Train 4, as 25 cars plus 75 cars adds up to 100 cars. Train 3 must be combined with Train 4, as 50 cars plus 50 cars equals 100 cars.Also, assume that there is always a way to fill each track with 100 trains. Make sure the output format puts the trains in ascending order (i.e. Train 1 and Train 3, not Train 3 and Train 1).
**Definitions**
Let $ T = \{t_1, t_2, t_3, t_4\} $ be a tuple of four positive integers representing the lengths (number of carts) of four trains.
Let $ S = \{ (i,j) \mid 1 \leq i < j \leq 4 \text{ and } t_i + t_j = 100 \} $ be the set of valid train pairs.
**Constraints**
1. $ t_i \in \mathbb{Z}^+ $ for $ i \in \{1,2,3,4\} $
2. There exists at least one pair $ (i,j) \in S $ such that $ t_i + t_j = 100 $
3. Exactly two disjoint pairs $ (i,j), (k,l) \in S $ exist, partitioning $ \{1,2,3,4\} $
**Objective**
Output the two pairs in $ S $, sorted lexicographically (i.e., each pair $ (i,j) $ with $ i < j $, and the set of pairs ordered by increasing first index).