#include <iostream>
#include <cstring>
#include <algorithm>

using namespace std;
const int N = 220;
int a[N];
int b[N];
int main()
{
    int n;
    cin>>n;
    int sum1 = 0;
    int sum2 = 0;
    for(int i = 0;i<n;i++)
    {
        cin>>a[i];
        if(a[i]<0) sum1+=a[i];
        else sum2+=a[i];
    }
    cout<<sum2-sum1;
}