In Japan, if there's one day between two holidays, this day is considered a holiday. Given a binary string of length $n$ that represents $n$ days, count the total number of holidays.

Input

The first and only line of input contains a single string of length $n$ ($1 \leq n \leq 10^5$) consisting only of $1$'s and $0$'s, where a $1$ represents a holiday and a $0$ represents a normal day.

Output

Output a single integer, the total number of holidays after counting the extra holidays.