You are given a string s consisting of lowercase English letters.

Parse the string from left to right and identify valid English words representing single digits from "zero" to "nine" (specifically "zero", "one", "two", "three", "four", "five", "six", "seven", "eight", and "nine"). Convert each identified word into its corresponding numeric digit from $0$ to $9$. Any characters or fragments that do not form a valid number word are ignored and skipped.

Return the resulting string of digits.

Constraints:

• $1 \leq$ s.length $\leq 10^5$

• s contains only lowercase English letters.

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