A12146 | Interstellar battle

The first line contains one integer number $N$ ( $1 \le N \le 10^5$ ) denoting the number of planets in Bubbledom (numbered from $0$ to $N-1$ ).

The next line contains $N$ different real numbers in the interval $[0,1]$ , specified with 2 digits after the decimal point, denoting the probabilities that the corresponding planet will fall.

The next $N-1$ lines contain all the wormholes in Bubbledom, where a wormhole is specified by the two planets it connects.

The next line contains a positive integer $Q$ ( $1 \le Q \le 10^5$ ), denoting the number of enemy attacks.

The next $Q$ lines each contain a non-negative integer and a real number from interval $[0,1]$ , denoting the planet the government of Bubbledom decided to reinforce or weaken, along with the new probability that the planet will fall.

Output contains $Q$ numbers, each of which represents the expected number of kingdoms that are left after each enemy attack. Your answers will be considered correct if their absolute or relative error does not exceed $10^{-4}$ .

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