from sortedcontainers import SortedDict, SortedList, SortedSet
from collections import Counter, deque, defaultdict
from heapq import heapify, heappop, heappush, nlargest, nsmallest
from bisect import bisect_left, bisect, bisect_right
from itertools import permutations, combinations, combinations_with_replacement, product, accumulate
from more_itertools import pairwise, windowed, powerset, distinct_permutations, set_partitions
from math import gcd, lcm, isqrt
from string import ascii_lowercase, ascii_uppercase, digits
from copy import deepcopy
from time import perf_counter
from functools import lru_cache, cache, reduce, cmp_to_key, total_ordering
import sys
import os
from typing import Any, List, Callable
import pypyjit

from atcoder.fenwicktree import FenwickTree
from atcoder.segtree import SegTree
from atcoder.lazysegtree import LazySegTree
from atcoder.string import suffix_array, lcp_array, z_algorithm
from atcoder.math import inv_mod, crt, floor_sum
from atcoder.convolution import convolution, convolution_int
from atcoder.modint import ModContext, Modint
from atcoder.dsu import DSU
from atcoder.maxflow import MFGraph
from atcoder.mincostflow import MCFGraph
from atcoder.scc import SCCGraph
from atcoder.twosat import TwoSAT


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

    N = input()
    print(N + N)


if __name__ == "__main__":
    main()