Given a list of student score entries, find the student with the highest average score.

Each element in marks is a single string in the format studentName,score, where:

• the part before the comma is the student name
• the part after the comma is the score as a string

A student may appear multiple times, meaning that student has multiple scores.

Return the name of the student whose average score is the highest.

Important details:

• Scores can be positive, zero, or negative.
• The score part should be converted to an integer before processing.
• The average is the arithmetic mean of all scores for that student.
• Compare students using the exact average value. Do not use floor, ceil, rounding, or integer division for comparison.
• If a student appears only once, that score itself is the average.
• If multiple students have the same highest average, return the lexicographically smaller name.
• Assume the input contains at least one entry.

String highestAverageScore(List<String> marks)

• Each string represents one entry in the format studentName,score.
• Return the student name whose average score is the highest.

Example:

• "Jethiya,20"
• "Bida,50"

• 1 ≤ marks.size()
• Each entry contains exactly one student name and one score.
• Each entry contains exactly one comma.
• Each score string is a valid integer representation.
• Student names are non-empty strings.
• Student names do not contain commas.

Return a String representing the student name with the maximum average score.

Example 1:

Method call: highestAverageScore(marks = List.of("Jethiya,20", "Bida,50", "Iyer Idli,99", "Jethiya,25"))

Average scores:

• Jethiya = (20 + 25) / 2 = 22.5
• Bida = 50
• Iyer Idli = 99

Output: "Iyer Idli"


Example 2:

Method call: highestAverageScore(marks = List.of("Alice,-10", "Bob,-5", "Alice,0"))

Average scores:

• Alice = (-10 + 0) / 2 = -5
• Bob = -5

Both students have the same highest average, so return the lexicographically smaller name.

Output: "Alice"


Example 3:

Method call: highestAverageScore(marks = List.of("Ravi,30"))

Ravi appears once, so his average is 30.

Output: "Ravi"