Problem Description

Navigate a maze with teleportation portals. The maze has walls (#), paths (.), start (S), end (E), and teleport portals marked with letters (A-Z). Portals with the same letter are connected and allow instant teleportation between them.

Input Format

First line contains m and n (maze dimensions). Next m lines contain the maze with characters: S (start), E (end), # (wall), . (path), A-Z (portals).

Output Format

Minimum steps to reach end from start, or -1 if impossible.

Constraints

• 1 ≤ m, n ≤ 50

• Exactly one S and one E

• Teleportation between same letters is instant (0 steps)

• Regular movement takes 1 step

• Can have multiple portal pairs

Sample Input/Output

4 5
S.#.E
..#..
A.#.B
A...B

4

Explanation

Path: S→(0,1)→A(2,0)→teleport to A(3,0)→(3,1)→(3,2)→(3,3)→B(3,4)→teleport to B(2,4)→E(0,4). Steps: 4.