11=1+10
11 = 2+9
11=3+8
11=4+7
11=5+6
21=1+20
21=2+19
21=3+18
21=4+17
21=5+16
21=6+15
21=7+14
21=8+13
21=9+12
21=10+11
44 = 1+43
44=2+42
44=3+41
44=4+40
44=4+39
44=6+38
44=7+37
44=8+36
44=9+35
44=10+34
44=11+33
44=12+32
44=13+31
44=14+30
44=15+29
44=16+28
......
0=0+0
