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UKSPC Practice Problems » Tickets

Source
driver.c, driver.cpp, or driver.java
Input
standard input
Output
standard output

You have an infinite line of people, who are numbered with natural numbers, 1 through infinity. But tickets are not given out strictly FIFO, but in rounds. In round 1, the first person is given a ticket. In all subsequent ith rounds, the first person in line and every ith person after them is given a ticket. Once you have a ticket, you are removed from the line. Given a natural number n < MAX_INT, report the (ordinal) number of the first person to receive a ticket in the nth round.

Sample Input

5

Abbreviated Sample Output

7