#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define BEGIN_STACK_EXTEND(size)                                                                                  \
    void *stack_extend_memory_ = malloc(size);                                                                    \
    void *stack_extend_origin_memory_;                                                                            \
    char *stack_extend_dummy_memory_ = (char *)alloca((1 + (int)(((long long)stack_extend_memory_) & 127)) * 16); \
    *stack_extend_dummy_memory_ = 0;                                                                              \
    asm volatile("mov %%rsp, %%rbx\nmov %%rax, %%rsp"                                                             \
                 : "=b"(stack_extend_origin_memory_)                                                              \
                 : "a"((char *)stack_extend_memory_ + (size)-1024));
#define END_STACK_EXTEND                                                 \
    asm volatile("mov %%rax, %%rsp" ::"a"(stack_extend_origin_memory_)); \
    free(stack_extend_memory_);
#define mod 1000000007ll
#define loop(i, n) for (int i = 0; i < n; i++)
#define flagcount(bit) __builtin_popcount(bit)
#define flag(x) (1ll << x)
#define flagadd(bit, x) bit |= flag(x)
#define flagpop(bit, x) bit &= ~flag(x)
#define flagon(bit, i) bit &flag(i)
#define flagoff(bit, i) !(bit & (1ll << i))
#define all(v) v.begin(), v.end()
#define putout(a) cout << a << '\n'
#define Sum(v) accumulate(all(v), 0ll)
template <typename T>
bool chmax(T &a, const T &b)
{
    if (a < b)
    {
        a = b; // aをbで更新
        return true;
    }
    return false;
}
template <typename T>
bool chmin(T &a, const T &b)
{
    if (a > b)
    {
        a = b; // aをbで更新
        return true;
    }
    return false;
}
void AS(ll X, ll L, ll R) { assert(L <= X && X <= R); }
int main()
{
    //cout << fixed << setprecision(10);
    /*
    x,x+1,x+2,...x+N-1
    Nx+N(N-1)/2
    N{x+(N-1)/2}
    N%2=0のとき、N=2nとして、n{2x+(N-1)}
    n(N+1),n(N+3),n(N+5),...となる。これらは全てnの倍数だがそれ以上ではない
    N%2=1のとき、N=2n-1として、N{x+(n-1)}
    N(n),N(n+1),...
    */
    ll N;
    cin >> N;
    if (N % 2 == 0)
        putout(N / 2);
    else
        putout(N);
    return 0;
}