For problem statement at 0-999/500-599/570-579/575/problemD.txt this is a correct solution, but verifier at 0-999/500-599/570-579/575/verifierD.go ends with reference failed: exec: "refD_bin": executable file not found in $PATH can you fix the verifier? ```go
package main

import (
	"fmt"
)

func main() {
	var operations [][4]int

	// Forward sweep
	// Check column 2 twice
	operations = append(operations, [4]int{2, 1, 2, 2})
	operations = append(operations, [4]int{2, 1, 2, 2})

	// Check columns 3 to 999
	for x := 3; x <= 999; x++ {
		operations = append(operations, [4]int{x, 1, x, 2})
	}

	// Backward sweep
	// Check columns 999 down to 2
	for x := 999; x >= 2; x-- {
		operations = append(operations, [4]int{x, 1, x, 2})
	}

	fmt.Println(len(operations))
	for _, op := range operations {
		fmt.Printf("%d %d %d %d\n", op[0], op[1], op[2], op[3])
	}
}
```