function *main() {
  const N = +(yield);
  const A = (yield).split(" ").map(s => +s).sort((a, b) => b*b - a*a);
  let count = 0;
  const B = A.map(a => {
    if (a < 0) {
      count++;
      a = -a;
    }
   	return a;
  });
  
  if (count % 2 != 0) {
    B[B.length-1] *= -1;
  }
  
  const sum = B.reduce((a, b) => a + b);
  console.log(sum);
}

const iter = main();
iter.next();
require("readline").createInterface({input: process.stdin}).on("line", l => iter.next(l));