Competitive extraction of unique slice elements

Given an array of integers: values := []int{3, 3, 2, 1, 2, 1, 1, 2, 4}. You need to print each distinct element exactly once, using multiple goroutines. The order of output does not matter, but there should be no duplicates. In the original example, a data race occurs when writing to a regular map, leading to incorrect results. You need to fix the code to ensure safe concurrent access to the shared structure (for example, using a mutex or sync.Map).

func main() {
 values := []int{3, 3, 2, 1, 2, 1, 1, 2, 4}
 var idx sync.Map

 for _, v := range values {
  go func(val int) {
   if _, ok := idx.Load(val); ok {
    return
   }
   idx.Store(val, struct{}{})
   log.Println(val)
  }(v)
 }
}