While the age-old question of why chickens cross roads has been addressed in
great depth by the scientific community, surprisingly little has been published
in the research literature on the related subject of cow crossings. Farmer
John, well-aware of the importance of this issue, is thrilled when he is
contacted by a local university asking for his assistance in conducting a
scientific study of why cows cross roads. He eagerly volunteers to help.

As part of the study, Farmer John has been asked to document the number of times
each of his cows crosses the road. He carefully logs data about his cows'
locations, making a series of \(N\) observations over the course of a single day.
Each observation records the ID number of a cow (an integer in the range
\(1 \ldots 10\), since Farmer John has 10 cows), as well as which side of the road
the cow is on.

Based on the data recorded by Farmer John, please help him count the total
number of confirmed crossings. A confirmed crossing occurs when a consecutive
sightings of a cow place it on different sides of the road.

Problem credits: Brian Dean

Problem credits: Brian Dean

The first line of input contains the number of observations, \(N\), a positive
integer at most 100. Each of the next \(N\) lines contains one observation, and
consists of a cow ID number followed by its position indicated by either zero or
one (zero for one side of the road, one for the other side).

Please compute the total number of confirmed crossings.

riseoj 작성

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