Monkeys and Peaches

Problem Background

Special for beginners, ^_^

Problem Description

There is a pile of peaches on the beach, and $N$ monkeys come to divide them. The first monkey splits the pile into $N$ equal parts, with one peach left over; it throws that extra peach into the sea and takes away one part. The second monkey then splits the remaining peaches into $N$ equal parts, again with one left over, throws it into the sea, and takes away one part. The third, fourth, ..., and $N$-th monkeys each do the same: split the remaining peaches into $N$ equal parts, throw away the one extra, and take one part.

Write a program that, given the number of monkeys $N$, outputs the minimum number of peaches on the beach such that every monkey can get its share.

Input Format

One integer $N$.

Output Format

Output the minimum number of peaches on the beach when the number of monkeys is $N$. The result is guaranteed to fit in an int.

Sample Input

2

Sample Output

7

Constraints

1s, 1024KiB for each test case.