Does a direct road connect the three cities?#9419
There are three cities, and the distances between each pair of these cities are provided: a_{12} (between the first and second city), a_{13} (between the first and third city), and a_{23} (between the second and third city). The sequence of the cities along the road connecting them might not correspond to their numerical order; for instance, city number might be the first in the sequence. Using the distances a_{12}, a_{13}, a_{23}, determine:
1) if the cities are aligned on a straight road; 2) which city is positioned between the other two.
Provide the values a_{12}, a_{13}, a_{23}, separated by spaces, via the standard input.
If the cities are aligned on a straight road, print the number of the city that is situated between the other two to the standard output. If the cities are not connected by a straight road, print zero to the standard output.
Example 1