CF913H Don't Exceed

You generate real numbers $ s_{1},s_{2},...,s_{n} $ as follows: - $ s_{0}=0 $ ; - $ s_{i}=s_{i-1}+t_{i} $ , where $ t_{i} $ is a real number chosen independently uniformly at random between 0 and 1, inclusive. You are given real numbers $ x_{1},x_{2},...,x_{n} $ . You are interested in the probability that $ s_{i}

The first line contains integer $ n $ ( $ 1

Print a single integer, the answer to the problem.

In the first example, the sought probability is 1 since the sum of $ i $ real numbers which don't exceed 1 doesn't exceed $ i $ . In the second example, the probability is $ x_{1} $ itself. In the third example, the sought probability is $ 3/8 $ .