#!/usr/bin/env python3
d, T, i = [input() for _ in range(6)], [0] * 442, 416
while (i := i - 1) >= 0 and ([a := i % 26, b := i // 26] or 1) or print(["impossible", T[0]][T[0] < 50]):
    T[i] = min([[T[i - a + 26 + [x := ord(d[j][b]) - 65, 20][x == 16]] + (j + 3) // 4, 50][a > x] for j in range(6)])