"use strict";
const main = arg => {
  const Nums = arg.split("\n");
  const amount = Nums[0]*1;
  const arr = Nums[1].split(" ").map(x=> x*1).sort((a, b) => a - b);
  let ans = arr[0];
  for(let i = 1;i < amount; i++){
  	ans = (ans + arr[i])/2
  }
  
  console.log(ans);
}

main(require('fs').readFileSync('/dev/stdin', 'utf8'));
