#include<cstdio>
#include<bitset>
using namespace std;
const int Maxn = 500000;
int num[Maxn+5];
int tmp;
bitset<10000000> bit1;
void store()
{
    num[0] = 0;
    bit1[0] = 1;
    for(int i = 1;i<=Maxn;++i)
    {
        num[i] = num[i-1] - i;
        if(num[i]<0||bit1[num[i]])
            num[i] += 2*i;
        bit1[num[i]] = 1;
    }
}
int main()
{
    store();
    int n;
    while(scanf("%d",&n)&&n!=-1)
    printf("%d\n",num[n]);
    return 0;
}