The king gold as wages paid to loyal knight.

Description questions

The king gold as wages paid to loyal knight. The first day, Knight received a gold coin; two days (days two and three) years, received two gold coins every day; three days later (fourth, five or six days), the received three daily gold coins; four days later (seventh, eight, nine, ten) years, received four gold ...... this day payroll mode will always continue like this: when N N consecutive days to receive gold coins every day, Knights N + 1 consecutive days after, the coins received N + 1 (N is any positive integer) every day. You need to write a program to determine from the first day of a given number of days, the Knights won a total of how many gold coins.

Input Format

An integer (range of 1 to 10000), the number of days.

Output Format

Knight gold coins obtained.

Sample input

6

Sample Output

14

#include <stdio.h>
int main()
{
    int n,i,j,k,sum;
    while(scanf("%d",&n)!=EOF)
    {
        sum=0; j=1; k=1;
        for(i=1;i<=n;i++){
            sum+=k;
            if(i==j){
                k++;  //k表示当天可获得的金币数
                j+=k; //j表示金币能增加时需要跨过的天数
            }
        }
        printf("%d\n",sum);
    }
    return 0;
}