Does anyone know the answer?

Answer: 59
Step-by-step explanation:
Sum(-28 through -1) is returned to zero by sum(1 through 28), plus the integer 0.
This is 28*2+1 integers (57)
The next two in the series Sum(29 & 30) equal the desired 59.
This is a total of 57 + 2 integers = 59 integers