from math import sqrt

"""
This program tries all circle placements of the given radii in the statement that are close together
Comparing these with 25.4*2 we can check how much precision is required to do the comparisons correctly.
"""
rs = [25, 28, 32, 40, 50, 65, 80, 90, 100, 130, 160]
worst=1
for dx in range(1000):
    for dy in range(dx,1000):
        for r in rs:
            for r2 in rs:
                res = sqrt(dx*dx+dy*dy)-r/2-r2/2-25.4*2
                worst=min(worst,abs(res))
print(worst)