A space explorer's ship crashed on Mars! They send a series of SOS messages to Earth for help.

Letters in some of the SOS messages are altered by cosmic radiation during transmission. Given the signal received by Earth as a string, $\boldsymbol{\mathrm{~S~}}$, determine how many letters of the SOS message have been changed by radiation.

Example

$s=\text{'SOSTOT'}$

The original message was SOSSOS. Two of the message's characters were changed in transit.

Function Description

Complete the marsExploration function in the editor below.

marsExploration has the following parameter(s):

string s: the string as received on Earth

Returns

int: the number of letters changed during transmission

Input Format

There is one line of input: a single string, $\boldsymbol{\mathrm{~S~}}$.

Constraints

$1\leq\ \text{length of}\ s\leq99$
$\textbf{length of}~s~\textbf{modulo}~~3=0$
$\boldsymbol{\mathrm{~S~}}$ will contain only uppercase English letters, ascii[A-Z].

Sample Input 0
SOSSPSSQSSOR

Sample Output 0
3

Explanation 0

$\boldsymbol{\mathrm{~S~}}$ = SOSSPSSQSSOR, and signal length $\textbf{|s|}=\textbf{12}$. They sent $4$ SOS messages (i.e.: $12/3=4$).

Expected signal: SOSSOSSOSSOS
Recieved signal: SOSSPSSQSSOR
Difference: X X X

Sample Input 1
SOSSOT

Sample Output 1
1

Explanation 1

$\boldsymbol{\mathrm{~S~}}$ = SOSSOT, and signal length $|s|=6$. They sent $2$ SOS messages (i.e.: $6/3=2$).

Expected Signal: SOSSOS
Received Signal: SOSSOT
Difference: X

Sample Input 2
SOSSOSSOS

Sample Output 2
0

Explanation 2

Since no character is altered, return 0.

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