B"Today, Wet Shark is given n bishops on a 1000 by 1000 grid. Both rows and columns of the grid are numbered from 1 to 1000. Rows are numbered from top to bottom, while columns are numbered from left to right. Wet Shark thinks that two bishops attack each other if they share the same diagonal. Note, that this is the only criteria, so two bishops may attack each other (according to Wet Shark) even if there is another bishop located between them. Now Wet Shark wants to count the number of pairs of bishops that attack each other. The first line of the input contains n (1 xe2 x80 x89 xe2 x89 xa4 xe2 x80 x89n xe2 x80 x89 xe2 x89 xa4 xe2 x80 x89200 xe2 x80 x89000) -- the number of bishops. Each of next n lines contains two space separated integers xi and yi (1 xe2 x80 x89 xe2 x89 xa4 xe2 x80 x89xi, xe2 x80 x89yi xe2 x80 x89 xe2 x89 xa4 xe2 x80 x891000) -- the number of row and the number of column where i-th bishop is positioned. It's guaranteed that no two bishops share the same position. Output one integer -- the number of pairs of bishops which attack each other. In the first sample following pairs of bishops attack each other: (1, xe2 x80 x893), (1, xe2 x80 x895), (2, xe2 x80 x893), (2, xe2 x80 x894), (3, xe2 x80 x894) and (3, xe2 x80 x895). Pairs (1, xe2 x80 x892), (1, xe2 x80 x894), (2, xe2 x80 x895) and (4, xe2 x80 x895) do not attack each other because they do not share the same diagonal."...