Edit in JSFiddle

<div class="flex-container">
<div class="item item1">1</div>
<div class="item item2">2</div>
<div class="item">3</div>
<div class="item item4">4</div>
<div class="item">5</div>
</div>

.flex-container{
display: flex;
align-items: flex-start;
padding: 15px;
border: 2px solid #e2e2e2;
height: 200px;

}
.item{
  flex: 0 1 100px;
  background-color: #2da192;
  text-align: center;
  line-height: 100px;
  font-size: 30px;
  margin: 5px;
  font-weight: 600;
  color: #fff;
}