Substring Position Finder

Easy

You are given two strings: a main text string and a pattern string. Your task is to locate the first position where the pattern appears as a contiguous sequence within the text. Return the starting index (0-based) of the first occurrence of the pattern within the text. If the pattern does not exist anywhere in the text, return -1. This is a fundamental string matching problem that forms the basis of many text processing algorithms used in search engines, text editors, and data analysis tools.

Input

text = "sadbutsad"
pattern = "sad"

Output

Explanation

The pattern "sad" appears at indices 0 and 6 within the text "sadbutsad". Since we need the first occurrence, we return index 0.

Input

text = "onenoughtone"
pattern = "onenx"

Output

-1

Explanation

The pattern "onenx" does not occur in "onenoughtone", so we return -1.

Input

text = "helloworld"
pattern = "world"

Output

Explanation

The pattern "world" appears starting at index 5 in the text "helloworld".

Constraints