Find Index of the First Occurrence in a String

Easy

Description

You are given two strings, haystack and needle. Find the first place where needle appears inside haystack.

Return the index (counting from 0) where it starts. If needle does not appear in haystack, return -1.

Example 1:

Input: haystack = "mumbaimetro", needle = "metro"
Output: 6
Explanation: "metro" starts at index 6.

Example 2:

Input: haystack = "banana", needle = "nab"
Output: -1
Explanation: "nab" does not appear anywhere in "banana".

Example 3:

Input: haystack = "aaaab", needle = "aab"
Output: 2
Explanation: The first "a" at index 0 starts "aaa", which fails. The match starts at index 2.

3 shown

Example 1

Input

"mumbaimetro"
"metro"

Output

Example 2

Input

"banana"
"nab"

Output

-1

Example 3

Input

"aaaab"
"aab"

Output

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