#
# See ../README.md
#

#
# Run as: bc ch-2.bc < input-file
#

diff_per_minute =  11
min_per_hour    =  60
full_circle     = 720

while (1) {
    hours = read ()
    if (hours == -1) {
        break
    }
    minutes = read ()

    #
    # Result scale to 0, otherwise % acts weirdly.
    #
    scale = 0
    angle = (diff_per_minute * (hours * min_per_hour + minutes)) % full_circle
    if (2 * angle >= full_circle) {
        angle = full_circle - angle
    }

    #
    # If the angle is an odd number of half degrees, we want 
    # a result ending in ".5", but if it's an even number of
    # half degrees, we don't want to end in ".0"
    #
    scale = angle % 2

    #
    # Little hack to print a half as "0.5"
    #
    if (angle == 1) {
        "0"
    }

    angle / 2
}