Problem7386--ABC276 —— A - Rightmost

7386: ABC276 —— A - Rightmost

[Creator : ]
Time Limit : 1.000 sec  Memory Limit : 256 MiB

Description

You are given a string S consisting of lowercase English letters.
If a appears in S, print the last index at which it appears; otherwise, print -1. (The index starts at 1.)

Input

The input is given from Standard Input in the following format:
$S$

Output

Print the answer.

Constraints

S is a string of length between 1 and 100 (inclusive) consisting of lowercase English letters.

Sample 1 Input

abcdaxayz

Sample 1 Output

7
a appears three times in S. The last occurrence is at index 7, so you should print 7.

Sample 2 Input

bcbbbz

Sample 2 Output

-1
a does not appear in S, so you should print -1.

Sample 3 Input

aaaaa

Sample 3 Output

5

Source/Category