const Main = input => {
  input = input.split("\n")

  const n = parseInt(input[0], 10)
  const arr = input[1].split(' ').map(v => parseInt(v, 10)).sort((a, b) => a > b)
  const rec = (i, memo) => (i != n) ? rec(i + 1, (memo + arr[i]) / 2) : memo

  console.log(rec(0, arr[0]))
}

Main(require("fs").readFileSync("/dev/stdin", "utf8"))