Isomorphic Strings

Two strings of the same length are isomorphic if you can replace each letter of s with another letter to get t, so that: the same letter always becomes the same letter, and different letters never become the same letter (no two letters map to one). A letter may map to itself. Strings of different lengths are never isomorphic.

Examples

Example 1

Input:

isomorphic_strings('egg', 'add')

Output:

True

e -> a, g -> d.

Example 2

Input:

isomorphic_strings('foo', 'bar')

Output:

False

o would need to become both a and r.

Constraints

• 0 <= len(s), len(t) <= 3 * 10**5
• Both strings contain lower-case letters.