source_code: 
  // LM10: The next Ballon d'or
  import java.util.*;
  import java.io.*;
  import java.math.*;
  import javafx.util.Pair;
  public class Main
  {
      static class FastReader
      {
          private InputStream mIs;private byte[] buf = new byte[1024];private int curChar,numChars;public FastReader() { this(System.in); }public FastReader(InputStream is) { mIs = is;}
          public int read() {if (numChars == -1) throw new InputMismatchException();if (curChar >= numChars) {curChar = 0;try { numChars = mIs.read(buf);} catch (IOException e) { throw new InputMismatchException();}if (numChars <= 0) return -1; }return buf[curChar++];}
          public String nextLine(){int c = read();while (isSpaceChar(c)) c = read();StringBuilder res = new StringBuilder();do {res.appendCodePoint(c);c = read();}while (!isEndOfLine(c));return res.toString() ;}
          public String next(){int c = read();while (isSpaceChar(c)) c = read();StringBuilder res = new StringBuilder();do {res.appendCodePoint(c);c = read();}while (!isSpaceChar(c));return res.toString();}
          public long l(){int c = read();while (isSpaceChar(c)) c = read();int sgn = 1;if (c == '-') { sgn = -1 ; c = read() ; }long res = 0; do{ if (c < '0' || c > '9') throw new InputMismatchException();res *= 10 ; res += c - '0' ; c = read();}while(!isSpaceChar(c));return res * sgn;}
          public int i(){int c = read() ;while (isSpaceChar(c)) c = read();int sgn = 1;if (c == '-') { sgn = -1 ; c = read() ; }int res = 0;do{if (c < '0' || c > '9') throw new InputMismatchException();res *= 10 ; res += c - '0' ; c = read() ;}while(!isSpaceChar(c));return res * sgn;}
          public double d() throws IOException {return Double.parseDouble(next()) ;}
          public boolean isSpaceChar(int c) { return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1; }
          public boolean isEndOfLine(int c) { return c == '\n' || c == '\r' || c == -1; }
          public void scanIntArr(int [] arr){ for(int li=0;li<arr.length;++li){ arr[li]=i();}}
          public void scanLongArr(long [] arr){for (int i=0;i<arr.length;++i){arr[i]=l();}}
          public void shuffle(int [] arr){ for(int i=arr.length;i>0;--i) { int r=(int)(Math.random()*i); int temp=arr[i-1]; arr[i-1]=arr[r]; arr[r]=temp; } }
      }
      public static void main(String[] args)throws IOException {
          /*
  inputCopy
  4
  2 1 2 1
  outputCopy
  4
  inputCopy
  5
  0 -1 -1 -1 -1
  outputCopy
  4
  */
          PrintWriter pw = new PrintWriter(System.out);
          FastReader fr = new FastReader();
          int n=fr.i();
          int [] arr=new int[n];
          fr.scanIntArr(arr);
          int min=Integer.MAX_VALUE;
          int max=Integer.MIN_VALUE;
          long sum=0;
          if(n==1)
          {
              pw.println(arr[0]);
              pw.flush();
              pw.close();
              return;
          }
          for(int i=0;i<n;++i)
          {
              if(arr[i]<min)
                  min=arr[i];
              if(arr[i]>max)
                  max=arr[i];
              sum+=Math.abs(arr[i]);
          }
          if(min>0)
          {
              sum-=2*min;
          }
          if(max<0)
          {
              sum+=2*max;
          }
          pw.println(sum);
          pw.flush();
          pw.close();
      }
  }