input:

3
1
111
110110
1101010
1111
111111

output:

-1
308
6 6
3 3
3 4
3 4
4 5
4 5
4 5
5 6
5 6
5 6
6 7
6 7
6 7
7 8
7 8
7 8
8 9
8 9
8 9
9 10
9 10
9 10
10 11
10 11
10 11
11 12
11 12
11 12
12 13
12 13
12 13
13 14
13 14
13 14
14 15
14 15
14 15
15 16
15 16
15 16
16 17
16 17
16 17
17 18
17 18
17 18
18 19
18 19
18 19
19 20
19 20
19 20
20 21
20 21
20 21
21 2...

result:

wrong answer (l,r) is invalid (test case 2)