const n = parseInt(readline()), inputs = readline().split(' ');
if(n == 0) return console.log(0);
var diff = 0 - Math.abs(inputs[0]), res = inputs[0];
for(let el of inputs) {
    if(0 - Math.abs(el) >= diff) {
        diff = 0 - Math.abs(el);
        res = el;
        if(inputs.includes(Math.abs(el))) res = Math.abs(el);
    }
}

console.log(res);