DWITE Online Computer Programming Contest
December 2010
Problem 1
Integers along a line

When talking about points on the Cartesian plane, most people tend to deal only with points with integer coordinates (i.e. points whose x and y coordinates are integers). Given a line segment with integer coordinates, you are curious about how many points on the line segment (other than the endpoints) have integer coordinates.

The input file DATA1.txt will contain 5 lines, each line having 4 integers -1000 <= A,B,X,Y <= 1000, where (A,B) describes one endpoint of a line, and (X,Y) describes another.

The output file OUT1.txt will contain 5 lines, each line containing the number of points along the line (not including the endpoints) that fall on the integer coordinates.

Sample Input (first 2 shown):
0 0 2 2
-1 -2 1 1
		        
Sample Output (first 2 shown):
1
0