import sys
#sys.setrecursionlimit(10 ** 6)
INF = float('inf')
#10**20,2**63に変えるのもあり
MOD = 10**9 + 7
MOD2 = 998244353
from collections import defaultdict
def ceil(A,B):
    return -(-A//B)
def solve():
    def II(): return int(sys.stdin.readline())
    def LI(): return list(map(int, sys.stdin.readline().split()))
    def LC(): return list(input())
    def IC(): return [int(c) for c in input()]
    def MI(): return map(int, sys.stdin.readline().split())
    A = II()
    #B-A<x<B+A
    #-A<x<A
    print((A-1)*2+1)
    return
solve()