var lines = [];
var reader = require('readline').createInterface({
  input: process.stdin,
  output: process.stdout
});
reader.on('line', function (line) {
  lines.push(line);
});
process.stdin.on('end', function () {
  const INPUT = lines.split("\n");
	const count = INPUT[0];
  const values = INPUT[1].split(" ");
  
  /* Parse Int */
	for(var i = 0; i < count; i++) {
    values[i] = values[i] - 0;
  }

  // 昇順
  values.sort(function(a,b){ return a - b; });

  // Minimum
  var previous = values[0];
  for(var i = 1; i < count; i++) {
		previous = (previous + values[i]) / 2;
	}
	console.log(previous);
});