19-2=17,12+3=15,13+4=17,14+4=18,18-5=13,17-6=11,13-9=4,11-3=8,10+8=18,15-7=8,9+8=17;
7+7=14,8+8=16,9+9=18,19-1=18,19-7=12,13+5=18,16-4=12,15-5=10,11+7=18,13+6=19,13-8=5,17-3=14,14-9=5,11+2=13,13+2=15,18-9=9,12-6=6,10-3=7,19-5=14,18-18=0,10-7=3,11-9=2,15-15=0,18-9=9