function solution(numbers, target) {
let answer=0;
const DFS=(index, sum)=>{
if (index<=numbers.length){
if (index===numbers.length){
if(sum===target){
answer+=1;
}
}else{
DFS(index+1, sum+numbers[index])
DFS(index+1, sum-numbers[index])
}
}
}
DFS(0,0)
return answer;
}