HS08TEST: Getting WA

What’s wrong with this one.
Im getting a runtime error

X,Y = (float(tmp) for tmp in raw_input().split(’ '))

if X>0 and X%5==0 and X+0.5<=Y : Y=Y-X-0.5

print("%.2f"%Y)

questions is http://www.codechef.com/problems/HS08TEST

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