k = int(input().strip())
a=['0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0','0']
n = 2*k+1
i=0
sum1 = 0
for i in range(k):
    a[i] = n
    sum1 += a[i]
sum1 = sum1 + 2*k 
print(sum1)