Substring with Concatenation of All Words

Given a string s and an array of strings words of the same length, find all starting indices of substring(s) in s that is a concatenation of each word in words exactly once and without any intervening characters. The first line contains the string s, the second line contains an integer m (1 <= m <= 100), and the third line contains m space-separated words. Output all starting indices of the substring(s). Example: Input: barfoothefoobarman 3 a foo the Output: 0 9