def best_time(flight_info, current_city, destination_city):
    """that takes the following information and returns the shortest time possible to get back home. If there is no way to get home, the function returns infinity. """

    lines = flight_info.splitlines()
    header = lines[0]

    q = int(header.split()[1])


    mat = [[float('inf') for i in range(q)] for i in range(q)]
    is_directed = header[0] == 'D'

    for item in lines[1:]:
        numbers = [int(i) for i in item.split()]
        s = numbers[0]
        e = numbers[1]
        w = numbers[2]
        mat[s][e] = w
        if not is_directed:
            mat[e][s] = w
    for i in range(q):
        mat[i][i] = 0
    if current_city == destination_city:
        return 0
    else:
        for k in range(q):
            for i in range(q):
                for j in range(q):
                    if mat[i][j] > mat[i][k] + mat[k][j]:
                        mat[i][j] = mat[i][k] + mat[k][j]
        return mat[current_city][destination_city]