在flexbox中，如何将下一行元素推到上一行的右上角元素，而没有负边距？

<style>
  .container {
    display: flex;
    flex-wrap: wrap-reverse;
    justify-content: flex-end;
    align-items: flex-start;
  }
  
  .item {
    flex: 0 0 auto;
    margin: 10px;
    width: 100px;
    height: 100px;
    background-color: #ccc;
  }
</style>

<div class="container">
  <div class="item">1</div>
  <div class="item">2</div>
  <div class="item">3</div>
  <div class="item">4</div>
  <div class="item">5</div>
  <div class="item">6</div>
</div>