Hey! I solved this problem and here are some test that you may check for you solution:

0->10
1->1
2->2
3->3
4->4
5->5
6->6
7->7
8->8
9->9
10->25
11->-1
12->26
13->-1
14->27
15->35
16->28
17->-1
18->29
19->-1
20->45
21->37
22->-1
23->-1
24->38
25->55
26->-1
27->39
28->47
29->-1
30->56
31->-1
32->48
33->-1
34->-1
35->57
36->49
37->-1
38->-1
39->-1
40->58
41->-1
42->67
43->-1
44->-1
45->59
46->-1
47->-1
48->68
49->77
50->255
51->-1
52->-1
53->-1
54->69
55->-1
56->78
57->-1
58->-1
59->-1
60->256
61->-1
62->-1
63->79
64->88
65->-1
66->-1
67->-1
68->-1
69->-1
70->257
71->-1
72->89
73->-1
74->-1
75->355
76->-1
77->-1
78->-1
79->-1
80->258
81->99
82->-1
83->-1
84->267
85->-1
86->-1
87->-1
88->-1
89->-1
90->259
91->-1
92->-1
93->-1
94->-1
95->-1
96->268
97->-1
98->277
99->-1
100->455

Good Luck!

I have checked for my solution. All done. But I have "Wrong answer" at test 8.....

try this test:
732421875
result must be:
3555555555555

and this:

0
(result: 10)

1
(result: 1)

Edited by author 15.06.2011 14:32

Oh! Thanks!!!

thanks!)

Shouldn't the test value for

1 be 11 and so on for single digit numbers?

Thank a lot man