B. Cows

**单点时限: **10.0 sec

**内存限制: **1024 MB

Farmer John has recently moved to EOJ Town so that he could buy beautiful (and delicious) cows. But soon, he found that prices of cows at EOJ Town increases at a ridiculous speed. Namely, when Farmer John arrived at EOJ Town, the cows sold dollar; on the second day, it became dollars; on the third day, it became dollars – the price doubles as time goes by! Soon the price became unacceptable to Farmer John, and he left EOJ Town, disappointed, as he could no longer even afford one cow with his salary.

Farmer John has a daily salary of dollars. He wants to know the total number of cows he can purchase during his stay. That is, if you don’t have the patience to read this **short** statement, the following formula:

A positive integer ().

Input

4

Output

7

Input

16

Output

31

Input

64

Output

127

已结束

NaN

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