// Mini-VM library (function-based) with a tiny JSON extractor
// Safe MVP: no real JSON parsing; string scan for first int literal only

static box MiniVm {
  _is_digit(ch) { return ch == "0" || ch == "1" || ch == "2" || ch == "3" || ch == "4" || ch == "5" || ch == "6" || ch == "7" || ch == "8" || ch == "9" }

  // Read consecutive digits starting at pos
  read_digits(json, pos) {
    @out = ""
    loop (true) {
      @s = json.substring(pos, pos+1)
      if s == "" { break }
      if _is_digit(s) { out = out + s  pos = pos + 1 } else { break }
    }
    return out
  }

  // Extract the first integer literal from our AST JSON v0 subset
  parse_first_int(json) {
    @key = "\"value\":{\"type\":\"int\",\"value\":"
    @idx = json.lastIndexOf(key)
    if idx < 0 { return "0" }
    @start = idx + key.length()
    return read_digits(json, start)
  }

  // Execute a minimal program: print the extracted integer and exit code 0
  run(json) {
    @n = parse_first_int(json)
    print(n)
    return 0
  }
}