The Amestris government has been alerted of cities, numbered
to
. However, they are going to be slowly reopening roads, at a steady rate of
road per day, for days
to
. knows their plan, and will only move between two cities if he knows that they are in the same strangely connected component. He will ask
queries in the form "
", asking the first day on which
and
will be strangely connected, or
if it will never be strangely connected.
Note: We define a strangely connected component as a connected component that will not be disconnected by removing any 1 edge.
Input Specification
First line:
Next lines:
integers
and
, representing that cities
and
are connected on the
day.
Next lines:
integers
and
, representing a query.
Subtasks
For full points, .
For 5/25 points, .
Sample Input
4 5 3
3 3
1 3
3 0
3 2
2 3
0 2
3 3
0 3
Sample Output
-1
0
-1
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