===== ISTEM =====
Solve the following programming task.

TASK: TIK Register Machine

Write a function 'runTik(program)' that runs a program written in TIK, a small made-up language, and returns an array of the numbers it outputs.

Program text:
- Instructions are separated by newlines. Leading and trailing spaces on a line are ignored.
- Lines that are empty (or only spaces) and lines whose first non-space character is '#' are ignored and are not instructions.
- Within an instruction, tokens are separated by one or more spaces.

Machine:
- There are four registers named a, b, c and d. All start at 0.
- Every value stored in a register is reduced to the range 0..999 by taking it modulo 1000, always giving a non-negative result (for example -1 becomes 999 and 1003 becomes 3).
- An integer literal is an optional '-' followed by one or more digits ('+5' and '5.0' are not valid).
- An operand written as X below is either a register name or an integer literal. Its value is the register's value, or the literal reduced to 0..999 in the same way.

Instructions (R must be a register name, N must be an integer literal):
- set R X: R becomes the value of X.
- add R X: R becomes R plus the value of X.
- mul R X: R becomes R times the value of X.
- out X: appends the value of X to the output.
- jmp X N: if the value of X is not 0, the next instruction is the one N instructions away from this one (N may be negative; ignored lines are not counted). Otherwise execution continues with the next instruction.
Instruction names and register names are lowercase; anything else is invalid.

Running:
- Before running anything, check the whole program. If any line that is not ignored is not a valid instruction (unknown name, wrong number of operands, or an invalid register, literal or operand), throw an Error whose message is 'bad instruction at line K', where K is the 1-based line number of the first such line in the original text, counting ignored lines too. In that case nothing is run.
- Execution starts at the first instruction and stops normally when the next instruction position is before the first instruction or after the last one.
- A program may execute at most 10,000 instructions. If it has not stopped after executing 10,000 instructions, throw an Error with the message 'step limit'.

STARTER CODE (javascript):
function runTik(program) {
  // Write your code here
}

module.exports = { runTik };


RULES:
- Keep the function name and signature EXACTLY as given.
- Return working code only. No explanations.
- Put the code in a single ``` block.
- Try to solve it first. If you genuinely cannot, write only this single
  line instead of producing faulty code: CANNOT_SOLVE

===== HAM YANIT =====
```javascript
function runTik(program) {
  const lines = program.split('\n');
  const instrs = [];
  const registers = { a: 0, b: 0, c: 0, d: 0 };
  const isReg = (s) => /^[abcd]$/.test(s);
  const isLit = (s) => /^-?\d+$/.test(s);
  const reduce = (v) => ((v % 1000) + 1000) % 1000;
  const evalOperand = (token) => {
    if (isReg(token)) return registers[token];
    // literal
    return reduce(parseInt(token, 10));
  };

  const expectedArgs = {
    set: 2,
    add: 2,
    mul: 2,
    out: 1,
    jmp: 2,
  };

  for (let i = 0; i < lines.length; i++) {
    const raw = lines[i];
    const trimmed = raw.trim();
    if (trimmed === '' || trimmed[0] === '#') continue; // ignored line

    const parts = trimmed.split(/\s+/);
    const op = parts[0];
    if (!expectedArgs.hasOwnProperty(op)) {
      throw new Error(`bad instruction at line ${i + 1}`);
    }
    if (parts.length - 1 !== expectedArgs[op]) {
      throw new Error(`bad instruction at line ${i + 1}`);
    }

    if (op === 'set' || op === 'add' || op === 'mul') {
      const [R, X] = parts.slice(1);
      if (!isReg(R) || !(isReg(X) || isLit(X))) {
        throw new Error(`bad instruction at line ${i + 1}`);
      }
      instrs.push({ type: op, r: R, x: X });
    } else if (op === 'out') {
      const [X] = parts.slice(1);
      if (!(isReg(X) || isLit(X))) {
        throw new Error(`bad instruction at line ${i + 1}`);
      }
      instrs.push({ type: op, x: X });
    } else if (op === 'jmp') {
      const [X, N] = parts.slice(1);
      if (!(isReg(X) || isLit(X))) {
        throw new Error(`bad instruction at line ${i + 1}`);
      }
      if (!isLit(N)) {
        throw new Error(`bad instruction at line ${i + 1}`);
      }
      instrs.push({ type: op, x: X, offset: parseInt(N, 10) });
    }
  }

  const output = [];
  let ip = 0;
  let steps = 0;

  while (ip >= 0 && ip < instrs.length) {
    if (steps >= 10000) throw new Error('step limit');
    const instr = instrs[ip];
    steps++;

    switch (instr.type) {
      case 'set': {
        registers[instr.r] = evalOperand(instr.x);
        ip++;
        break;
      }
      case 'add': {
        const val = evalOperand(instr.x);
        registers[instr.r] = reduce(registers[instr.r] + val);
        ip++;
        break;
      }
      case 'mul': {
        const val = evalOperand(instr.x);
        registers[instr.r] = reduce(registers[instr.r] * val);
        ip++;
        break;
      }
      case 'out': {
        output.push(evalOperand(instr.x));
        ip++;
        break;
      }
      case 'jmp': {
        const cond = evalOperand(instr.x);
        if (cond !== 0) {
          ip = ip + instr.offset;
        } else {
          ip++;
        }
        break;
      }
    }
  }

  return output;
}

module.exports = { runTik };
```