def median(seq):
    if N % 2 == 1:
        return seq[(N-1)//2]
    else:
        return (seq[N//2-1]+seq[N//2]) / 2

N = int(input())
Y = list(sorted((map(int, input().split()))))
med = median(Y)
ans = sum(abs(Y_i - med) for Y_i in Y)

print(ans)