Problem	sumstack
User	LL
Submission Time	2025-06-17 17:12:15
Score	0
Max Time	N/A
Max Memory	N/A

Compile Error

sumstack.cpp: In function ‘int main()’:
sumstack.cpp:23:20: error: invalid types ‘<unresolved overloaded function type>[long long int]’ for array subscript
23 | ans += vec.at[j];
| ^