import math

line1 = "Physics Scores  15  12  8   8   7   7   7   6   5   3"
line2 = "History Scores  10  25  17  11  13  17  20  13  9   15"

x = [int(e) for e in line1.split()[2:]]
y = [int(e) for e in line2.split()[2:]]

n = len(x)
ex = sum(x)/n
ey = sum(y)/n
cov = sum([(xi-ex)*(yi-ey) for (xi,yi) in zip(x,y)])
stdx = math.sqrt(sum([(xi-ex)**2 for xi in x]))
stdy = math.sqrt(sum([(yi-ey)**2 for yi in y]))
result = cov/(stdx*stdy)
print(f"{result:.3f}")