람다 넣어서 쓸때
n번째 요소에서 진행중일때 n+1번째 요소를 지시할 수 있는 방법 있음?
https://stackoverflow.com/questions/3752019/how-to-get-the-index-of-a-value-in-a-vector-using-for-each
https://stackoverflow.com/questions/3752019/how-to-get-the-index-of-a-value-in-a-vector-using-for-each