"use strict";
    
const main = arg => {
    arg = arg.trim().split("\n");
    const N = parseInt(arg[0]);
    let v = arg[1].split(" ").map(n=>parseInt(n)).sort((a,b)=>a-b);
    
    while(v.length !== 1) {
        let x = v[0];
        let y = v[1];
        
        let temp = (x + y) / 2;
        
        v.shift();
        v.shift();
        
        v.unshift(temp);
        
        v.sort((a,b)=>a-b);
    }
    
    console.log(v[0]);
}
main(require('fs').readFileSync('/dev/stdin', 'utf8'));