Final answer:
The variable y should likely be initialized to 0 before reaching the first decision symbol as it represents the starting point of accumulation. The variable a should be initialized to a specific constant value determined by the problem's parameters.
Step-by-step explanation:
The initialization of the variables a and y is a critical step in setting up a mathematical model or algorithm. Considering that the context revolves around the accumulation of years and decision-making, proper initialization is necessary to start computations meaningfully.
Generally, when a process starts at the beginning, it's common to set an accumulative variable, such as y, to 0, indicating that no time has elapsed or no accumulation has occurred yet. Hence, before reaching the first decision symbol in a programming or mathematical process, one would often initialize the dependent variable y to 0, indicating the start point of accumulation.
On the other hand, a appears to be a constant and its value would be determined by the specific circumstances or parameters of the problem at hand. Without additional context, it's not possible to determine the exact value for a, but it should be initialized to whatever value is determined by those parameters.