from collections import Counter, deque, defaultdict
from heapq import heapify, heappop, heappush, nlargest, nsmallest
from bisect import bisect_left, bisect, bisect_right
from string import ascii_lowercase, ascii_uppercase, digits
from copy import deepcopy
from time import perf_counter
import sys
import os
from typing import Any, List, Callable


IS_LOCAL = os.environ.get("LOCAL") == "true"


def debug(*args, sep=" ", end="\n", flush=False) -> None:
    if IS_LOCAL:
        print(*args, sep=sep, end=end, file=sys.stderr, flush=flush)


def yn(flg: bool) -> bool:
    print('Yes' if flg else 'No')
    return flg


def gcd(a, b):
    a = abs(a); b = abs(b)
    if a < b: a, b = b, a
    while b > 0:
        a, b = b, a % b
    return a


def lcm(a, b):
    return a * b // gcd(a, b)


def main():
    readline = sys.stdin.readline
    inf = 1e18
    MOD = 998244353

    N = input()
    print(N + N)


if __name__ == "__main__":
    main()