Given two strings s and t, create a function to determine if they are isomorphic. Two strings are isomorphic if the characters in s can be replaced to get t. All occurrences of a character must be replaced with another character while preserving the order of characters. No two characters may map to the same character but a character may map to itself.

Examples

isIsomorphic("xade", "tesh") ➞ true

isIsomorphic("egg", "add") ➞ true

isIsomorphic("aba", "baa") ➞ false

isIsomorphic("paper", "title") ➞ true

Notes

Use either string s or t as your mapping reference.