55+66
121
55-66
-11
55+66-77
44
123+654
777
654-123
531
123+789-654
258
567+71
638
567-71
496
2123+2789-654
4258
4567+8971
13538
8971-4567
4404
4567-109+255
4713
10357+7452
17809
10357-7452
2905
10357-359+6254
16252