Almost all young man know Monkey Sun whose name is Sun Wukong. One day he steals many peaches from the kingdom of heaven. First day, he ate a half of the peaches, then ate another one of the left peaches.The next day, he ate a half of the left peaches, then another one.Until the n-th day ,before he ate he found only one peach. Please help Sun Wukong to calculate how many peaches he took from the kingdom of heaven.

The input file contains one or more test cases, each line is the days N(1 < n < 30).

For each test case, output a line indicating the number of peaches Monkey Sun had the first day.

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