def interQuartile(values, freqs): # Create the data set S S = [] for i in range(len(values)): S += [values[i]] * freqs[i]

S = sorted(S)
n = len(S)

def median(sub_arr):
    sub_n = len(sub_arr)
    mid = sub_n // 2
    if sub_n % 2 == 0:
        return (sub_arr[mid - 1] + sub_arr[mid]) / 2.0
    else:
        return sub_arr[mid]

# Calculate Q1
lower_half = S[:n // 2]
Q1 = median(lower_half)

# Calculate Q3
if n % 2 == 0:
    upper_half = S[n // 2:]
else:
    upper_half = S[(n // 2) + 1:]
Q3 = median(upper_half)

# Print the interquartile range to 1 decimal place
print(f"{Q3 - Q1:.1f}")

if name == 'main': n = int(input().strip()) values = list(map(int, input().rstrip().split())) freqs = list(map(int, input().rstrip().split()))

# Ensure that the number of elements in S is equal to the sum of freqs
assert len(values) == len(freqs), "The length of values and freqs must be the same"
assert sum(freqs) <= 1000, "The sum of frequencies must be less than or equal to 1000"

interQuartile(values, freqs)