import java.util.Scanner;
class BeeNums {
public static void main
(String[] args
) {
Scanner s
= new Scanner
(System.
in); long a = 0;
while((a=s.nextLong()) != -1)
{
long last = 1;
for(int i=0;i<a;i++)
{
last = last + i*6;
if(last == a)
{
break;
}
else if(last>a)
{
break;
}
}
}
}
}
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