Black Cut Cake

Describe

As we all know, black skin was born and January 01, 1000, that day, dark clouds, thunder and lightning, in the black light pierced the night sky, the dark skin accurately generated the boy. may wish to say to everyone: because he is born black, so named Black skin. ^-^ to celebrate the 1006 birthday of black skin, which is January 01, 2006. The headmaster held a large celebration for him at the school called the "Genius of the Day". Students and their families are invited to attend. Considering the large number of people at that time, the black friend small Jia Jia special for him from the United States imported a super invincible spiced spicy yin and yang Five elements to make thousands of hungry ghosts for the Juedao Big Mac Cake No. 1th.     For the enjoyment of all persons present at the scene. Black also takes into account the number of people too much, cake and only one. So decided to use the fewest number of knives to draw the most cake copies. For example: Start is 1 cakes, the number of copies is 1, the black skin a knife down, the number of knives is 1, the number of copies is 2, another knife, the number of knives is 2, the number of copies is 4; another knife ...     Some knives go down, the number of copies is n. Black skin at that time, thousand hearts million bitter finally crossed out. He wants to know if you can also draw it out. ^-^

Input

Enter a number that is the number of knives to be drawn at the time of the black skin. 0< =n< = 34567890;

Output

A number, that is, the number of people on the scene. The number of known people is the same as the number of copies of the Black Peel.

Sample input

2

Sample output

4

#include <stdio.h>int  main () {    __int64 n;      while (~SCANF ("%i64d",&N))    {        printf ("%i64d\n", (n+1) *n/2+1 );    }     return 0 ;}

Black Cut Cake