A-B-C-D-E-F | | | | | | G-H-I-J-K-L | | | | | | M-N-O-P-Q-R | | | | | | S-T-U-V-W-XA man born in A (and never ventured outside his city) has to visit a man in X but wants to take a detour to get there. He wants to visit every city but not enter any city more than once during his tour. How should his trip go?