The return of the King

Mr. King typed the grades of a literature student into an online average calculator. Only after he finished did he notice that his return key was broken. He meant to put each grade on its own line, but every grade went in on a single line with nothing between them.

Each grade is an integer between 1 and 10, written in base 10 without leading zeros. If the student's grades were 3, 10, 1 and 10, the screen shows 310110.

Given the run-together string $S$, compute the student's average grade.

The first line contains a non-empty string $S$ of at most 100 base 10 digits.

There is exactly one way to split $S$ into pieces such that each piece is an integer between 1 and 10 written without leading zeros.

Print the average grade with exactly two digits after the decimal point.

Round at the third decimal digit, and round a value that falls exactly halfway upward. If the average is 1.125, print 1.13.