#include <bits/stdc++.h>
using namespace std;

int main()
{
    int N;
    cin >> N;
    vector<int> A(N);
    for (int i = 0; i < N; i++)
    {
        cin >> A[i];
    }
    long long plus = 0;
    long long minus = 0;
    for (int i = 0; i < N; i++)
    {
        if (A[i] >= 0)
        {
            plus += A[i];
        }
        else
        {
            minus += -A[i];
        }
    }
    cout << plus - minus;
}