readline();
let data = readline().split(' ');
data = data.map(val => parseInt(val));
data.sort((v1, v2) => v1 - v2);
const head = data[0],
      tail = data[data.length - 1];
data = data.map(val => Math.abs(val));
let sum = data.reduce((pre, cur) => pre + cur);
if (head > 0 || tail < 0) {
  sum -= data[0] * 2;
  print(sum);
}else {
  print(sum);
}