from math import sqrt, floor


def tour(friends, friend_towns, home_to_town_distances):
    print(friends, friend_towns, home_to_town_distances)
    total_km = 0
    friends = [x for x in friends for j in range(len(friend_towns)) if x in friend_towns[j] ]
    friend_towns = [x for x in friend_towns if x[0] in friends]
    for i in range(len(friends)):
        for j in range(len(friend_towns)):
            if friends[i] in friend_towns[j]:
                if i == 0:
                    total_km += home_to_town_distances[friend_towns[j][1]]
                    break
                else:
                    total_km += sqrt(home_to_town_distances[friend_towns[j][1]] ** 2 -
                                     home_to_town_distances[friend_towns[j - 1][1]] ** 2)
                    break

    total_km += home_to_town_distances[friend_towns[j][1]]
    return floor(total_km)