import numpy as np

N =int(input())
xdata =[i for i in range(N)]
ydata =list(map(float,input().split()))
cov = np.cov(xdata,ydata)
varx =cov[0][0]
vary =cov[1][1]
covxy =cov[1][0]
meany = np.mean(ydata)
meanx = np.mean(xdata)
print(covxy)
A = covxy / varx
B = meany -A*meanx
C = (vary -(covxy**2)/varx)*(N-1)
print(B,A)
print(C)