Blue Bridge Cup practice system number sequence summation (Python)

Problem description

seek 1+2+3+…+n Value .

Input format

Input includes an integer n.

Output format

Output one line , Include an integer , Express 1+2+3+…+n Value .

Reference code

n = int(input())
print((n*(1+n))//2)

Investigate knowledge points

If you use for Cycle accumulation will run timeout
Use the summation formula of the arithmetic sequence , But be careful to use integral division //
Python Division in