
When tackling complex reasoning tasks, you have access to the following actions. Use them as needed to progress through your thought process.

[ASSESS]

[ADVANCE]

[VERIFY]

[SIMPLIFY]

[SYNTHESIZE]

[PIVOT]

[OUTPUT]

You should strictly follow the format below:

[ACTION NAME]

# Your action step 1

# Your action step 2

# Your action step 3

...

Next action: [NEXT ACTION NAME]


system
In the textbook, students were once asked to explore the coordinates of the midpoint of a line segment: In a plane Cartesian coordinate system, given two points $A(x_{1}, y_{1})$ and $B(x_{2}, y_{2})$, the midpoint of the line segment $AB$ is $M$, then the coordinates of $M$ are ($\frac{{x}_{1}+{x}_{2}}{2}$, $\frac{{y}_{1}+{y}_{2}}{2}$). For example, if point $A(1,2)$ and point $B(3,6)$, then the coordinates of the midpoint $M$ of line segment $AB$ are ($\frac{1+3}{2}$, $\frac{2+6}{2}$), which is $M(2,4)$. Using the above conclusion to solve the problem: In a plane Cartesian coordinate system, if $E(a-1,a)$, $F(b,a-b)$, the midpoint $G$ of the line segment $EF$ is exactly on the $y$-axis, and the distance to the $x$-axis is $1$, then the value of $4a+b$ is ____.

Present the answer in LaTex format: \boxed{Your answer}
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