Is any further optimization possible? (Codeforces)
Firstly you need to put all the global statements into a function because of Python code runs faster in a function compared to global scope.

You don't need the arr variable. You can just use 

x[i], y[i] = map(int, raw_input().split())


instead of using the two lines. map uses the function(1st argument) on each of the outputs from the second argument.

After placing the global statements into a function then instead of passing i, j, k you would need to pass the values directly.

I'll look up the algorithm and see if there are other changes that can be made.