'use strict';
const main = input => {
  const n = parseInt(input[0], 10);
  let v = input[1].split(' ').map(val => parseInt(val, 10));
  v.sort((x,y) => x>y?1:-1);
  for(let i=0; i<n-1; i++) {
    let ave = (v[0]+v[1])/2;
    v.shift();
    v.shift();
    v = [ave, ...v];
    // console.log(v);
  }
  console.log(v[0]);
};
main(require("fs").readFileSync("/dev/stdin", "utf8").split('\n'));