#include <bits/stdc++.h>
using namespace std;
int gcd(int a, int b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
int spf[100001];
unordered_map<int, set<int>> s;
void sieve() {
  spf[1] = 1;
  for (int i = 2; i < 100001; i++) spf[i] = i;
  for (int i = 4; i < 100001; i += 2) spf[i] = 2;
  for (int i = 3; i * i < 100001; i++) {
    if (spf[i] == i) {
      for (int j = i * i; j < 100001; j += i)
        if (spf[j] == j) spf[j] = i;
    }
  }
}
vector<int> getFactorization(int x, int i) {
  vector<int> ret;
  while (x != 1) {
    s[spf[x]].insert(i);
    ret.push_back(spf[x]);
    x = x / spf[x];
  }
  return ret;
}
int main() {
  int n;
  cin >> n;
  ;
  int arr[n];
  for (int i = 0; i < n; i++) cin >> arr[i];
  ;
  int max = INT_MIN;
  int min = INT_MAX;
  long long int sum1 = 0;
  long long int sum2 = 0;
  for (int i = 0; i < n; i++) {
    if (arr[i] < 0)
      sum2 = sum2 + arr[i];
    else
      sum1 = sum1 + arr[i];
  }
  cout << (sum1 - sum2);
  return 0;
}
