#r_1 -># #0#........#1#........#1#........#-3#

#r_2 -># #1#....#-1#........#1#........#-7#

#r_3 -># #1#........#1#........#0#............#2#

#r_1 = r_1 + r_2#

#1#........#0#........#2#........#-10#

#1#....#-1#........#1#........#-7#

#1#........#1#........#0#............#2#

#r_2 = r_1 - r_2#

#1#........#0#........#2#........#-10#

#0#........#1#........#1#........#-3#

#1#........#1#........#0#............#2#

#r_3 = r_3 - r_1#

#1#........#0#........#2#........#-10#

#0#........#1#........#1#........#-3#

#0#........#1#....#-2#...........#12#

#r_3 = r_3 - r_2#

#1#........#0#........#2#........#-10#

#0#........#1#........#1#........#-3#

#0#........#0#....#-3#...........#15#

#r_3 = r_3/-3#

#1#........#0#........#2#........#-10#

#0#........#1#........#1#........#-3#

#0#........#0#........#1#........#-5#

#r_2 = r_2 - r_3#

#1#........#0#........#2#........#-10#

#0#........#1#........#0#............#2#

#0#........#0#........#1#........#-5#

#r_1 = r_1 - 2r_3#

#1#........#0#........#0#...........#0#

#0#........#1#........#0#............#2#

#0#........#0#........#1#........#-5#