n = int(input())
a = list(map(int,input().split()))
A = sum(a)
B = sum([i*a[i] for i in range(n)])
b = (((2*n-1)*A)/3 - B)/((n**2+n)/6)
d = (B - ((n-1)*A)/2)/((n**3-n)/12)
c = sum([(a[i]-b-i*d)**2 for i in range(n)])
print(b,d)
print(c)