1 1
1 10
1 100
1 1000
10 10
10 100
10 1000
11 10
11 100
11 1000
15 10
15 100
15 1000
100 100
100 1000
101 100
101 1000
110 100
110 1000
900 1000
990 1000
998 1000
1000 1000
-1 -1