about loops(Pardon my poor English standard, thanks)

Question

I did a little altering on the coads below: in this program, you can type some numbers and add them on.
The time you are allowed to type in depends on the value you allocate to "n " at first . for example, if you wanna to add a,b,c on you're supposed to type in "3" firstly and type in a,b,c in a row. if you type in a number called d after c,"d" will be ignored.
But, the problem is that, if you only type in "a" and "b", the result it outputs will be( a+b+b).Why ?
Hope to get your help. Thanks a lot.

Answer 1

https://code.sololearn.com/c56VEsJ6pBl4/?ref=app

Answer 2

anybody here?