Explanation of the Problem

Task Overview

The problem requires determining which letter, 'a' or 'b', appears first in a given string input. It is guaranteed that both letters are present in the string.

Input

• A string containing both the letters 'a' and 'b'.

Output

• You need to print 'a' if it appears before 'b' in the string, or 'b' if it appears before 'a'.

Simple Approach to Solve the Problem

1. Read Input: Get the string input from the user.
2. Find Positions: Identify the position (index) of the first occurrence of 'a' and 'b' in the string.
3. Compare Positions:
   • If the index of 'a' is less than the index of 'b', it means 'a' comes first.
   • Otherwise, 'b' comes first.
4. Output Result: Print the letter that appears first.

Example Execution Steps

Input

Assume the input string is “caxby”.

Finding Positions

1. Find the index of 'a':
   • Index of 'a' = 1 (it is the second character).
2. Find the index of 'b':
   • Index of 'b' = 3 (it is the fourth character).

Comparison

• Compare the indexes:
  • Since 1 (index of 'a') < 3 (index of 'b'), 'a' is printed.

Output

Print 'a'.

Sample Code Snippet (Python)

# Read the input string from standard input
input_string = input().strip()

# Find the first occurrence of 'a' and 'b'
index_a = input_string.index('a')
index_b = input_string.index('b')

# Compare indexes and print the corresponding letter
if index_a < index_b:
    print('a')
else:
    print('b')

Summary

• Read the input string which includes both 'a' and 'b'.
• Determine the first occurrence of each letter.
• Compare their positions and print the one that appears first.

For further understanding of string operations and comparisons, exploring courses on the Enterprise DNA platform may be beneficial.