COCI '17 Contest 5 #5 Pictionary
View as PDFThere is a planet, in a yet undiscovered part of the universe, with a country inhabited solely by mathematicians. In this country, there are a total of  mathematicians, and the interesting fact is that each mathematician lives in their own city. It is also interesting that no two cities are connected with a road, because mathematicians can communicate online or by reviewing academic papers. Naturally, the cities are labeled with numbers from 
 to 
.
Life was perfect until one mathematician decided to write an academic paper on their smartphone. The smartphone auto-corrected the word "self-evident" to "Pictionary" and the paper was published as such. Soon after, the entire country discovered pictionary and wanted to meet up and play, so construction work on roads between cities began shortly.
The road construction will last a total of  days, according to the following schedule: on the first day, construction is done on roads between all pairs of cities that have 
 as their greatest common divisor. On the second day, construction is done on roads between all pairs of cities that have 
 as their greatest common divisor, and so on until the 
 day when construction is done on roads between all pairs of cities that are co-prime. More formally, on the 
 day, construction is done on roads between cities 
 and 
 if 
.
Since the mathematicians are busy with construction work, they've asked you to help them determine the minimal number of days before a given pair of mathematicians can play pictionary together.
Input Specification
The first line of input contains three positive integers , 
 and 
 
, the number of cities, the number of days it takes to build the roads, and the number of queries.
Each of the following  lines contains two distinct positive integers 
 and 
 
 that denote the cities of the mathematicians who want to find out the minimal number of days before they can play pictionary together.
Output Specification
The  line must contain the minimal number of days before the mathematicians from the 
 query can play pictionary together.
Scoring
In test cases worth  of total points, it will hold 
, 
.
Sample Input 1
8 3 3
2 5
3 6
4 8
Sample Output 1
3
1
2
Explanation for Sample Output 1
On the first day, road  is built. Therefore, the answer to the second query is 
.
On the second day, roads , 
, 
, 
 and 
 are built. Cities 
 and 
 are now connected (it is possible to get from the first to the second using city 
).
On the third day, roads between relatively prime cities are built, so cities  and 
 are connected.
Sample Input 2
25 6 1
20 9
Sample Output 2
4
Explanation for Sample Output 2
On the second day, road  is built, whereas on the fourth day, road 
 is built. After the fourth day, cities 
 and 
 are connected via city 
.
Sample Input 3
9999 2222 2
1025 2405
3154 8949
Sample Output 3
1980
2160
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