"use strict";
function Main(input) {
    let cin = new Inputer(input);
    let N = cin.getInt(), A = cin.getIntArray(N);
    let dp = new Array(N + 1).fill(0).map(() => new Array(2).fill(-1e10));
    dp[0][0] = 0;
    for (let n = 0; n < N; n++) {
        dp[n + 1][0] = Math.max(...[dp[n + 1][0], dp[n][0] + A[n], dp[n][1] - A[n]]);
        dp[n + 1][1] = Math.max(...[dp[n + 1][1], dp[n][0] - A[n], dp[n][1] + A[n]]);
    }
    console.log(dp[N][0]);
}
class Inputer{constructor(t){if(typeof t=='undefined')throw new Error('引数（stdin）を省略できません！');this.cnt=0,this.items=t.split(/\n|\s/)}getInt(){return this.items[this.cnt++]-0}getIntArray(t){if(typeof t=='undefined')throw new Error('引数（1以上）を省略できません！');let r=new Array(t);for(let e=0;e<t;e++)r[e]=this.getInt();return r}getStr(){return this.items[this.cnt++]}getStrArray(t){if(typeof t=='undefined')throw new Error('引数（1以上）を省略できません！');let r=new Array(t);for(let e=0;e<t;e++)r[e]=this.getStr();return r}}
if (typeof window == "undefined") Main(require("fs").readFileSync("/dev/stdin", "utf8"));