406195: GYM102307 I Integer Prefix
Description
The Unique Numerical Association of Language (UNAL) is an association created to conserve only numbers in different texts. In fact, numbers are so important for UNAL, that its lemma is: 'people can communicate only using digits'.
Mr. Potato Head, the head of the UNAL has assigned you a task to help them to achieve the goal of the association.
Given a text $$$T$$$ you have to find the longest non-empty prefix of $$$T$$$ consisting only of digits, for the UNAL this is enough to understand the whole text.
InputInput consists of a single line with a text $$$T$$$ without spaces.
The length of the text is between $$$1$$$ and $$$2 * 10^5$$$
OutputPrint one line with the longest non-empty numeric prefix of $$$T$$$, if there is no such prefix print $$$-1$$$ instead.
ExamplesInput23082019UNALOutput
23082019Input
_1234567890Output
-1