import sys
sys.setrecursionlimit(10**5)

n=int(input())
d=[1,2,3]
if n>=3:
    d=d+[0]*(n-2)
for i in range(3,n+1):
    d[i]=5*(i-3)+3
if n<3:
    print(d[n-1])
else:
    print(d[-1])