- Time limit: 1.00 s
- Memory limit: 512 MB
There are n cities in Byteland but no roads between them. However, each day, a new road will be built. There will be a total of m roads.
Your task is to process q queries of the form: "after how many days can we travel from city a to city b for the first time?"
The first input line has three integers n, m and q: the number of cities, roads and queries. The cities are numbered 1,2,\dots,n.
After this, there are m lines that describe the roads in the order they are built. Each line has two integers a and b: there will be a road between cities a and b.
Finally, there are q lines that describe the queries. Each line has two integers a and b: we want to travel from city a to city b.
For each query, print the number of days, or -1 if it is never possible.
- 1 \le n, m, q \le 2 \cdot 10^5
- 1 \le a,b \le n
5 4 3 1 2 2 3 1 3 2 5 1 3 3 4 3 5
2 -1 4