text: /****************************************************************************************
  *  @author: kzvd4729                                         created: Mar/06/2018 22:30                        
  *  solution_verdict: Accepted                                language: GNU C++14                               
  *  run_time: 15 ms                                           memory_used: 1900 KB                              
  *  problem: https://codeforces.com/contest/946/problem/A
  ****************************************************************************************/
  #include<bits/stdc++.h>
  using namespace std;
  int n,num,sum;
  int main()
  {
      ios_base::sync_with_stdio(0);
      cin.tie(0);
      cin>>n;
      for(int i=1;i<=n;i++)
      {
          cin>>num;
          sum+=abs(num);
      }
      cout<<sum<<endl;
      return 0;
  }