Smallest KMP

Chef has a string $S$. He also has another string $P$, called *pattern*. He wants to find the pattern in $S$, but that might be impossible. Therefore, he is willing to reorder the characters of $S$ in such a way that $P$ occurs in the resulting string (an anagram of $S$) as a substring. Since this problem was too hard for Chef, he decided to ask you, his genius friend, for help. Can you find th