Let's solve the expression step by step, following the order of operations (PEMDAS/BODMAS), which stands for Parentheses/Brackets, Exponents/Orders, Multiplication and Division (from left to right), Addition and Subtraction (from left to right).

1. Evaluate any multiplication and division first:
\(-25 \times 1 = -25\)

So the expression becomes:
\[12 + 15 + 16 - 25 + 2 + 8 - 312 + 15 + 16 - 25 + 2 + 8 - 3\]

\[12 + 15 + 16 - 25 + 2 + 8 - 312 + 15 + 16 - 25 + 2 + 8 - 3\]

Now, add and subtract from left to right:

2. Simplify the expression:

- Calculate \(12 + 15 = 27\)
- Add 16: \(27 + 16 = 43\)
- Subtract 25: \(43 - 25 = 18\)
- Add 2: \(18 + 2 = 20\)
- Add 8: \(20 + 8 = 28\)
- Subtract 312: \(28 - 312 = -284\)
- Add 15: \(-284 + 15 = -269\)
- Add 16: \(-269 + 16 = -253\)
- Subtract 25: \(-253 - 25 = -278\)
- Add 2: \(-278 + 2 = -276\)
- Add 8: \(-276 + 8 = -268\)
- Subtract 3: \(-268 - 3 = -271\)

Thus, the result of the expression is \(-271\).