#include <bits/stdc++.h>

using namespace std;

const int nmax = 2000 + 10;
int x[nmax];

int main()
{
    freopen("output1","w",stdout);

    int n = 2000; int b = 10;

    int mask = (1 << b) - 1;
    for (int i = 1; i <= n / 2; ++i)
        x[i] = (mask << b) | i;
    for (int i = 1; i <= n / 2; ++i)
        x[n/2+i] = (i << b) | mask;

    for (int i = 1; i <= n; ++i)
        printf("%d ", x[i]);

    return 0;
}