graph = [
    # KSR, Sek, Bahnhofstr, Hafenstrasse, Zelgstrasse, Bahnhof
    [ -1, 1, -1, -1, -1, -1],  # KSR
    [ 1, -1, 3, 5, 7, -1],     # Sek
    [ -1, 3, -1, -1, -1, 7],   # Bahnhofstrasse
    [ -1, 5, -1, -1, -1, 6],   # Hafenstrasse
    [ -1, 7, -1, -1, -1, 5],   # Zelgstrasse
    [ -1, -1, 7, 6, 5, -1],    # Bahnhof
]