.wrapper > div:nth-of-type(2n-1),

.wrapper > p:nth-of-type(2n){

  background: orange;

}

/*或者*/

.wrapper > div:nth-of-type(2n+1),

.wrapper > p:nth-of-type(2n){

  background: orange;

}

/*或者*/

.wrapper > div:nth-of-type(odd),

.wrapper > p:nth-of-type(even){

  background: orange;

}