function main(input) {
  input=input.trim();
  const n = parseInt(input.split("\n")[0], 10);
  var arrV = input.split('\n')[1].split(' ').map((n) => parseInt(n, 10));
    arrV.sort(function(a,b){
      if( a < b ) return -1;
      if( a > b ) return 1;
      return 0;
  });
  var ans=arrV[0];
  for(var i=0; i<n-1; i++){
    ans=(ans+arrV[i+1])/2
  }
  console.log(ans);
}
main(require('fs').readFileSync('/dev/stdin', 'utf8'));