Beginning Zeros

**English**RU

You have a string that consist only of digits. You need to find how many zero digits ("0") are at the beginning of the given string.

**Input: ** A string, that consist of digits.

**Output: ** An Int.

**Example:**

beginning_zeros('100') == 0 beginning_zeros('001') == 2 beginning_zeros('100100') == 0 beginning_zeros('001001') == 2 beginning_zeros('012345679') == 1 beginning_zeros('0000') == 4

**Precondition:**
*0-9*