const readline = require('readline');

const rl = readline.createInterface({
  input: process.stdin,
  output: process.stdout
});

rl.question('', (N) => {
  rl.question('', (str) => {
    const arr = str.split(' ');
    
    const sortedNums = nums.sort((a, b) => a - b);
    let averSum = sortedNums[0];
    for(let i = 1; i < parseInt(N); i++) {
      averSum = (averSum + sortedNums[i]) / 2;
    }
    console.log(averSum);
  });
});