How to find n-elements from a list that make up a given sum?

Question

Algorithms

Hello.
It is required to solve a problem with the following data:

• A list of a limited number of numbers (no more than 100), for example [102, 154, 310, 140, 250, 70, 120]
  
• A number, such as 700
  

Based on these data, you need to find the only set of the nth number of numbers from the list, the sum of which is as close as possible to a given number or equal to it.
You need either a description of the algorithm, or, at best, a ready-made solution (preferably python).

Answer 1

for the smartest
, the problem in general has no solution, by the way