#include <bits/stdc++.h>
using namespace std;
int num[300];
int main() {
  int n, a, minn = 99999, sum = 0, sum2 = 0;
  scanf("%d", &n);
  for (int i = 1; i <= n; i++) scanf("%d", &num[i]);
  for (int i = 1; i <= n; i++) sum += abs(num[i]);
  printf("%d\n", sum);
  return 0;
}
