#include <iostream>
#include <cmath>
using namespace std;

int x[100], nr;

int main() {
    int n;
    cin >> n;
    do {
        x[nr++] = n % 2;
        n /= 2;
    } while (n);
    for (int i = nr - 1; i > 0; i--)
        if (x[i - 1] == 1 && x[i] == 0) {
            swap(x[i - 1], x[i]);
            break;
        }
    int s = 0;
    int i = 0;
    for (int j = nr - 1; j >= 0; j--) {
        s += x[i] * pow(2, i++);
    }
    cout << s;
    return 0;
}