#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, i, sum1 = 0, sum2 = 0, a[200];
  cin >> n;
  for (i = 0; i < n; i++) {
    cin >> a[i];
    if (a[i] < 0) {
      sum2 += a[i];
    } else
      sum1 += a[i];
  }
  cout << sum1 - sum2;
  return 0;
}
