#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, sum = 0, sum1 = 0;
  cin >> n;
  int a[n];
  for (int i = 0; i < n; i++) {
    cin >> a[i];
    if (a[i] >= 0) {
      sum += a[i];
    } else
      sum1 += a[i];
  }
  cout << sum - sum1 << endl;
}
