1+2= 1+19= 1+15= 12+6= 20-10= 20-12= 19-13= 20-19= 10+10= 12+7=
13+2+5= 4+6+7+2= 9+10-2-10+1= 12-3-3+12-13= 12-2-2-2-2+10= 20-3-3-3-3-5-2=