First Non-Repeating Character

Medium Strings
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Problem Statement

Write a Python program to find the first non-repeating character in a string. Print ‘_’ if all characters repeat.

Input Format

A string s.

Output Format

Print the character or '_'.

Constraints

1 <= len(s) <= 100

Sample Input

swiss

Sample Output

w

Explanation

Count character occurrences and find the first one with a frequency of 1.

Starter Code

def first_non_repeating(s):
    # Write your code here
    pass

s = input()
print(first_non_repeating(s))

Limits

  • Time Limit: 1s
  • Memory Limit: 256MB

Embedded C Programming

Updated: March 15, 2026
Intermediate

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