I was trying to solve this problem
let, int moded = x % A here, the highest value of moded can be A-1;
but if we add some other numbers.. then.. (x % A1) + (x % A2) + .... + (x % An) then what can be the highest result if we add all the moded from Ai to An for this sequence?
for each Ai, if we take Ai-1, then the result will be maximum, but will there always exist an x if we were to get this maximum result?
There always exists such $$$m$$$.
Copy pasting from editorial.
Let $$$m=a_1*a_2...a_n$$$
Then $$$m-1$$$ is the required $$$x$$$.